1This is doc/gcj.info, produced by makeinfo version 4.8 from 2/scratch/mitchell/gcc-releases/gcc-4.2.1/gcc-4.2.1/gcc/java/gcj.texi. 3 4 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, 5Inc. 6 7 Permission is granted to copy, distribute and/or modify this document 8under the terms of the GNU Free Documentation License, Version 1.2 or 9any later version published by the Free Software Foundation; with the 10Invariant Sections being "GNU General Public License", the Front-Cover 11texts being (a) (see below), and with the Back-Cover Texts being (b) 12(see below). A copy of the license is included in the section entitled 13"GNU Free Documentation License". 14 15 (a) The FSF's Front-Cover Text is: 16 17 A GNU Manual 18 19 (b) The FSF's Back-Cover Text is: 20 21 You have freedom to copy and modify this GNU Manual, like GNU 22software. Copies published by the Free Software Foundation raise 23funds for GNU development. 24 25INFO-DIR-SECTION Software development 26START-INFO-DIR-ENTRY 27* Gcj: (gcj). Ahead-of-time compiler for the Java language 28END-INFO-DIR-ENTRY 29 30INFO-DIR-SECTION Individual utilities 31START-INFO-DIR-ENTRY 32* gcjh: (gcj)Invoking gcjh. 33 Generate header files from Java class files 34* gjnih: (gcj)Invoking gjnih. 35 Generate JNI header files from Java class files 36* jv-scan: (gcj)Invoking jv-scan. 37 Print information about Java source files 38* jcf-dump: (gcj)Invoking jcf-dump. 39 Print information about Java class files 40* gij: (gcj)Invoking gij. GNU interpreter for Java bytecode 41* gcj-dbtool: (gcj)Invoking gcj-dbtool. 42 Tool for manipulating class file databases. 43* jv-convert: (gcj)Invoking jv-convert. 44 Convert file from one encoding to another 45* grmic: (gcj)Invoking grmic. 46 Generate stubs for Remote Method Invocation. 47* grmiregistry: (gcj)Invoking grmiregistry. 48 The remote object registry. 49END-INFO-DIR-ENTRY 50 51 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, 52Inc. 53 54 Permission is granted to copy, distribute and/or modify this document 55under the terms of the GNU Free Documentation License, Version 1.2 or 56any later version published by the Free Software Foundation; with the 57Invariant Sections being "GNU General Public License", the Front-Cover 58texts being (a) (see below), and with the Back-Cover Texts being (b) 59(see below). A copy of the license is included in the section entitled 60"GNU Free Documentation License". 61 62 (a) The FSF's Front-Cover Text is: 63 64 A GNU Manual 65 66 (b) The FSF's Back-Cover Text is: 67 68 You have freedom to copy and modify this GNU Manual, like GNU 69software. Copies published by the Free Software Foundation raise 70funds for GNU development. 71 72 73File: gcj.info, Node: Top, Next: Copying, Up: (dir) 74 75Introduction 76************ 77 78This manual describes how to use `gcj', the GNU compiler for the Java 79programming language. `gcj' can generate both `.class' files and 80object files, and it can read both Java source code and `.class' files. 81 82* Menu: 83 84* Copying:: The GNU General Public License 85* GNU Free Documentation License:: 86 How you can share and copy this manual 87* Invoking gcj:: Compiler options supported by `gcj' 88* Compatibility:: Compatibility between gcj and other tools for Java 89* Invoking gcjh:: Generate header files from class files 90* Invoking gjnih:: Generate JNI header files from class files 91* Invoking jv-scan:: Print information about source files 92* Invoking jcf-dump:: Print information about class files 93* Invoking gij:: Interpreting Java bytecodes 94* Invoking gcj-dbtool:: Tool for manipulating class file databases. 95* Invoking jv-convert:: Converting from one encoding to another 96* Invoking grmic:: Generate stubs for Remote Method Invocation. 97* Invoking grmiregistry:: The remote object registry. 98* About CNI:: Description of the Compiled Native Interface 99* System properties:: Modifying runtime behavior of the libgcj library 100* Resources:: Where to look for more information 101* Index:: Index. 102 103 104File: gcj.info, Node: Copying, Next: GNU Free Documentation License, Prev: Top, Up: Top 105 106GNU GENERAL PUBLIC LICENSE 107************************** 108 109 Version 2, June 1991 110 111 Copyright (C) 1989, 1991 Free Software Foundation, Inc. 112 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA 113 114 Everyone is permitted to copy and distribute verbatim copies 115 of this license document, but changing it is not allowed. 116 117Preamble 118======== 119 120The licenses for most software are designed to take away your freedom 121to share and change it. By contrast, the GNU General Public License is 122intended to guarantee your freedom to share and change free 123software--to make sure the software is free for all its users. This 124General Public License applies to most of the Free Software 125Foundation's software and to any other program whose authors commit to 126using it. (Some other Free Software Foundation software is covered by 127the GNU Library General Public License instead.) You can apply it to 128your programs, too. 129 130 When we speak of free software, we are referring to freedom, not 131price. Our General Public Licenses are designed to make sure that you 132have the freedom to distribute copies of free software (and charge for 133this service if you wish), that you receive source code or can get it 134if you want it, that you can change the software or use pieces of it in 135new free programs; and that you know you can do these things. 136 137 To protect your rights, we need to make restrictions that forbid 138anyone to deny you these rights or to ask you to surrender the rights. 139These restrictions translate to certain responsibilities for you if you 140distribute copies of the software, or if you modify it. 141 142 For example, if you distribute copies of such a program, whether 143gratis or for a fee, you must give the recipients all the rights that 144you have. You must make sure that they, too, receive or can get the 145source code. And you must show them these terms so they know their 146rights. 147 148 We protect your rights with two steps: (1) copyright the software, 149and (2) offer you this license which gives you legal permission to copy, 150distribute and/or modify the software. 151 152 Also, for each author's protection and ours, we want to make certain 153that everyone understands that there is no warranty for this free 154software. If the software is modified by someone else and passed on, we 155want its recipients to know that what they have is not the original, so 156that any problems introduced by others will not reflect on the original 157authors' reputations. 158 159 Finally, any free program is threatened constantly by software 160patents. We wish to avoid the danger that redistributors of a free 161program will individually obtain patent licenses, in effect making the 162program proprietary. To prevent this, we have made it clear that any 163patent must be licensed for everyone's free use or not licensed at all. 164 165 The precise terms and conditions for copying, distribution and 166modification follow. 167 168 TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 169 0. This License applies to any program or other work which contains a 170 notice placed by the copyright holder saying it may be distributed 171 under the terms of this General Public License. The "Program", 172 below, refers to any such program or work, and a "work based on 173 the Program" means either the Program or any derivative work under 174 copyright law: that is to say, a work containing the Program or a 175 portion of it, either verbatim or with modifications and/or 176 translated into another language. (Hereinafter, translation is 177 included without limitation in the term "modification".) Each 178 licensee is addressed as "you". 179 180 Activities other than copying, distribution and modification are 181 not covered by this License; they are outside its scope. The act 182 of running the Program is not restricted, and the output from the 183 Program is covered only if its contents constitute a work based on 184 the Program (independent of having been made by running the 185 Program). Whether that is true depends on what the Program does. 186 187 1. You may copy and distribute verbatim copies of the Program's 188 source code as you receive it, in any medium, provided that you 189 conspicuously and appropriately publish on each copy an appropriate 190 copyright notice and disclaimer of warranty; keep intact all the 191 notices that refer to this License and to the absence of any 192 warranty; and give any other recipients of the Program a copy of 193 this License along with the Program. 194 195 You may charge a fee for the physical act of transferring a copy, 196 and you may at your option offer warranty protection in exchange 197 for a fee. 198 199 2. You may modify your copy or copies of the Program or any portion 200 of it, thus forming a work based on the Program, and copy and 201 distribute such modifications or work under the terms of Section 1 202 above, provided that you also meet all of these conditions: 203 204 a. You must cause the modified files to carry prominent notices 205 stating that you changed the files and the date of any change. 206 207 b. You must cause any work that you distribute or publish, that 208 in whole or in part contains or is derived from the Program 209 or any part thereof, to be licensed as a whole at no charge 210 to all third parties under the terms of this License. 211 212 c. If the modified program normally reads commands interactively 213 when run, you must cause it, when started running for such 214 interactive use in the most ordinary way, to print or display 215 an announcement including an appropriate copyright notice and 216 a notice that there is no warranty (or else, saying that you 217 provide a warranty) and that users may redistribute the 218 program under these conditions, and telling the user how to 219 view a copy of this License. (Exception: if the Program 220 itself is interactive but does not normally print such an 221 announcement, your work based on the Program is not required 222 to print an announcement.) 223 224 These requirements apply to the modified work as a whole. If 225 identifiable sections of that work are not derived from the 226 Program, and can be reasonably considered independent and separate 227 works in themselves, then this License, and its terms, do not 228 apply to those sections when you distribute them as separate 229 works. But when you distribute the same sections as part of a 230 whole which is a work based on the Program, the distribution of 231 the whole must be on the terms of this License, whose permissions 232 for other licensees extend to the entire whole, and thus to each 233 and every part regardless of who wrote it. 234 235 Thus, it is not the intent of this section to claim rights or 236 contest your rights to work written entirely by you; rather, the 237 intent is to exercise the right to control the distribution of 238 derivative or collective works based on the Program. 239 240 In addition, mere aggregation of another work not based on the 241 Program with the Program (or with a work based on the Program) on 242 a volume of a storage or distribution medium does not bring the 243 other work under the scope of this License. 244 245 3. You may copy and distribute the Program (or a work based on it, 246 under Section 2) in object code or executable form under the terms 247 of Sections 1 and 2 above provided that you also do one of the 248 following: 249 250 a. Accompany it with the complete corresponding machine-readable 251 source code, which must be distributed under the terms of 252 Sections 1 and 2 above on a medium customarily used for 253 software interchange; or, 254 255 b. Accompany it with a written offer, valid for at least three 256 years, to give any third party, for a charge no more than your 257 cost of physically performing source distribution, a complete 258 machine-readable copy of the corresponding source code, to be 259 distributed under the terms of Sections 1 and 2 above on a 260 medium customarily used for software interchange; or, 261 262 c. Accompany it with the information you received as to the offer 263 to distribute corresponding source code. (This alternative is 264 allowed only for noncommercial distribution and only if you 265 received the program in object code or executable form with 266 such an offer, in accord with Subsection b above.) 267 268 The source code for a work means the preferred form of the work for 269 making modifications to it. For an executable work, complete 270 source code means all the source code for all modules it contains, 271 plus any associated interface definition files, plus the scripts 272 used to control compilation and installation of the executable. 273 However, as a special exception, the source code distributed need 274 not include anything that is normally distributed (in either 275 source or binary form) with the major components (compiler, 276 kernel, and so on) of the operating system on which the executable 277 runs, unless that component itself accompanies the executable. 278 279 If distribution of executable or object code is made by offering 280 access to copy from a designated place, then offering equivalent 281 access to copy the source code from the same place counts as 282 distribution of the source code, even though third parties are not 283 compelled to copy the source along with the object code. 284 285 4. You may not copy, modify, sublicense, or distribute the Program 286 except as expressly provided under this License. Any attempt 287 otherwise to copy, modify, sublicense or distribute the Program is 288 void, and will automatically terminate your rights under this 289 License. However, parties who have received copies, or rights, 290 from you under this License will not have their licenses 291 terminated so long as such parties remain in full compliance. 292 293 5. You are not required to accept this License, since you have not 294 signed it. However, nothing else grants you permission to modify 295 or distribute the Program or its derivative works. These actions 296 are prohibited by law if you do not accept this License. 297 Therefore, by modifying or distributing the Program (or any work 298 based on the Program), you indicate your acceptance of this 299 License to do so, and all its terms and conditions for copying, 300 distributing or modifying the Program or works based on it. 301 302 6. Each time you redistribute the Program (or any work based on the 303 Program), the recipient automatically receives a license from the 304 original licensor to copy, distribute or modify the Program 305 subject to these terms and conditions. You may not impose any 306 further restrictions on the recipients' exercise of the rights 307 granted herein. You are not responsible for enforcing compliance 308 by third parties to this License. 309 310 7. If, as a consequence of a court judgment or allegation of patent 311 infringement or for any other reason (not limited to patent 312 issues), conditions are imposed on you (whether by court order, 313 agreement or otherwise) that contradict the conditions of this 314 License, they do not excuse you from the conditions of this 315 License. If you cannot distribute so as to satisfy simultaneously 316 your obligations under this License and any other pertinent 317 obligations, then as a consequence you may not distribute the 318 Program at all. For example, if a patent license would not permit 319 royalty-free redistribution of the Program by all those who 320 receive copies directly or indirectly through you, then the only 321 way you could satisfy both it and this License would be to refrain 322 entirely from distribution of the Program. 323 324 If any portion of this section is held invalid or unenforceable 325 under any particular circumstance, the balance of the section is 326 intended to apply and the section as a whole is intended to apply 327 in other circumstances. 328 329 It is not the purpose of this section to induce you to infringe any 330 patents or other property right claims or to contest validity of 331 any such claims; this section has the sole purpose of protecting 332 the integrity of the free software distribution system, which is 333 implemented by public license practices. Many people have made 334 generous contributions to the wide range of software distributed 335 through that system in reliance on consistent application of that 336 system; it is up to the author/donor to decide if he or she is 337 willing to distribute software through any other system and a 338 licensee cannot impose that choice. 339 340 This section is intended to make thoroughly clear what is believed 341 to be a consequence of the rest of this License. 342 343 8. If the distribution and/or use of the Program is restricted in 344 certain countries either by patents or by copyrighted interfaces, 345 the original copyright holder who places the Program under this 346 License may add an explicit geographical distribution limitation 347 excluding those countries, so that distribution is permitted only 348 in or among countries not thus excluded. In such case, this 349 License incorporates the limitation as if written in the body of 350 this License. 351 352 9. The Free Software Foundation may publish revised and/or new 353 versions of the General Public License from time to time. Such 354 new versions will be similar in spirit to the present version, but 355 may differ in detail to address new problems or concerns. 356 357 Each version is given a distinguishing version number. If the 358 Program specifies a version number of this License which applies 359 to it and "any later version", you have the option of following 360 the terms and conditions either of that version or of any later 361 version published by the Free Software Foundation. If the Program 362 does not specify a version number of this License, you may choose 363 any version ever published by the Free Software Foundation. 364 365 10. If you wish to incorporate parts of the Program into other free 366 programs whose distribution conditions are different, write to the 367 author to ask for permission. For software which is copyrighted 368 by the Free Software Foundation, write to the Free Software 369 Foundation; we sometimes make exceptions for this. Our decision 370 will be guided by the two goals of preserving the free status of 371 all derivatives of our free software and of promoting the sharing 372 and reuse of software generally. 373 374 NO WARRANTY 375 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO 376 WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE 377 LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 378 HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT 379 WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT 380 NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 381 FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE 382 QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE 383 PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY 384 SERVICING, REPAIR OR CORRECTION. 385 386 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN 387 WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY 388 MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE 389 LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, 390 INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR 391 INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 392 DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU 393 OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY 394 OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN 395 ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. 396 397 END OF TERMS AND CONDITIONS 398Appendix: How to Apply These Terms to Your New Programs 399======================================================= 400 401If you develop a new program, and you want it to be of the greatest 402possible use to the public, the best way to achieve this is to make it 403free software which everyone can redistribute and change under these 404terms. 405 406 To do so, attach the following notices to the program. It is safest 407to attach them to the start of each source file to most effectively 408convey the exclusion of warranty; and each file should have at least 409the "copyright" line and a pointer to where the full notice is found. 410 411 ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES. 412 Copyright (C) YEAR NAME OF AUTHOR 413 414 This program is free software; you can redistribute it and/or modify 415 it under the terms of the GNU General Public License as published by 416 the Free Software Foundation; either version 2 of the License, or 417 (at your option) any later version. 418 419 This program is distributed in the hope that it will be useful, 420 but WITHOUT ANY WARRANTY; without even the implied warranty of 421 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 422 GNU General Public License for more details. 423 424 You should have received a copy of the GNU General Public License 425 along with this program; if not, write to the Free Software 426 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA 427 428 Also add information on how to contact you by electronic and paper 429mail. 430 431 If the program is interactive, make it output a short notice like 432this when it starts in an interactive mode: 433 434 Gnomovision version 69, Copyright (C) YEAR NAME OF AUTHOR 435 Gnomovision comes with ABSOLUTELY NO WARRANTY; for details 436 type `show w'. 437 This is free software, and you are welcome to redistribute it 438 under certain conditions; type `show c' for details. 439 440 The hypothetical commands `show w' and `show c' should show the 441appropriate parts of the General Public License. Of course, the 442commands you use may be called something other than `show w' and `show 443c'; they could even be mouse-clicks or menu items--whatever suits your 444program. 445 446 You should also get your employer (if you work as a programmer) or 447your school, if any, to sign a "copyright disclaimer" for the program, 448if necessary. Here is a sample; alter the names: 449 450 Yoyodyne, Inc., hereby disclaims all copyright interest in the program 451 `Gnomovision' (which makes passes at compilers) written by James Hacker. 452 453 SIGNATURE OF TY COON, 1 April 1989 454 Ty Coon, President of Vice 455 456 This General Public License does not permit incorporating your 457program into proprietary programs. If your program is a subroutine 458library, you may consider it more useful to permit linking proprietary 459applications with the library. If this is what you want to do, use the 460GNU Library General Public License instead of this License. 461 462 463File: gcj.info, Node: GNU Free Documentation License, Next: Invoking gcj, Prev: Copying, Up: Top 464 465GNU Free Documentation License 466****************************** 467 468 Version 1.2, November 2002 469 470 Copyright (C) 2000,2001,2002 Free Software Foundation, Inc. 471 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA 472 473 Everyone is permitted to copy and distribute verbatim copies 474 of this license document, but changing it is not allowed. 475 476 0. PREAMBLE 477 478 The purpose of this License is to make a manual, textbook, or other 479 functional and useful document "free" in the sense of freedom: to 480 assure everyone the effective freedom to copy and redistribute it, 481 with or without modifying it, either commercially or 482 noncommercially. Secondarily, this License preserves for the 483 author and publisher a way to get credit for their work, while not 484 being considered responsible for modifications made by others. 485 486 This License is a kind of "copyleft", which means that derivative 487 works of the document must themselves be free in the same sense. 488 It complements the GNU General Public License, which is a copyleft 489 license designed for free software. 490 491 We have designed this License in order to use it for manuals for 492 free software, because free software needs free documentation: a 493 free program should come with manuals providing the same freedoms 494 that the software does. But this License is not limited to 495 software manuals; it can be used for any textual work, regardless 496 of subject matter or whether it is published as a printed book. 497 We recommend this License principally for works whose purpose is 498 instruction or reference. 499 500 1. APPLICABILITY AND DEFINITIONS 501 502 This License applies to any manual or other work, in any medium, 503 that contains a notice placed by the copyright holder saying it 504 can be distributed under the terms of this License. Such a notice 505 grants a world-wide, royalty-free license, unlimited in duration, 506 to use that work under the conditions stated herein. The 507 "Document", below, refers to any such manual or work. Any member 508 of the public is a licensee, and is addressed as "you". You 509 accept the license if you copy, modify or distribute the work in a 510 way requiring permission under copyright law. 511 512 A "Modified Version" of the Document means any work containing the 513 Document or a portion of it, either copied verbatim, or with 514 modifications and/or translated into another language. 515 516 A "Secondary Section" is a named appendix or a front-matter section 517 of the Document that deals exclusively with the relationship of the 518 publishers or authors of the Document to the Document's overall 519 subject (or to related matters) and contains nothing that could 520 fall directly within that overall subject. (Thus, if the Document 521 is in part a textbook of mathematics, a Secondary Section may not 522 explain any mathematics.) The relationship could be a matter of 523 historical connection with the subject or with related matters, or 524 of legal, commercial, philosophical, ethical or political position 525 regarding them. 526 527 The "Invariant Sections" are certain Secondary Sections whose 528 titles are designated, as being those of Invariant Sections, in 529 the notice that says that the Document is released under this 530 License. If a section does not fit the above definition of 531 Secondary then it is not allowed to be designated as Invariant. 532 The Document may contain zero Invariant Sections. If the Document 533 does not identify any Invariant Sections then there are none. 534 535 The "Cover Texts" are certain short passages of text that are 536 listed, as Front-Cover Texts or Back-Cover Texts, in the notice 537 that says that the Document is released under this License. A 538 Front-Cover Text may be at most 5 words, and a Back-Cover Text may 539 be at most 25 words. 540 541 A "Transparent" copy of the Document means a machine-readable copy, 542 represented in a format whose specification is available to the 543 general public, that is suitable for revising the document 544 straightforwardly with generic text editors or (for images 545 composed of pixels) generic paint programs or (for drawings) some 546 widely available drawing editor, and that is suitable for input to 547 text formatters or for automatic translation to a variety of 548 formats suitable for input to text formatters. A copy made in an 549 otherwise Transparent file format whose markup, or absence of 550 markup, has been arranged to thwart or discourage subsequent 551 modification by readers is not Transparent. An image format is 552 not Transparent if used for any substantial amount of text. 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For 569 works in formats which do not have any title page as such, "Title 570 Page" means the text near the most prominent appearance of the 571 work's title, preceding the beginning of the body of the text. 572 573 A section "Entitled XYZ" means a named subunit of the Document 574 whose title either is precisely XYZ or contains XYZ in parentheses 575 following text that translates XYZ in another language. (Here XYZ 576 stands for a specific section name mentioned below, such as 577 "Acknowledgements", "Dedications", "Endorsements", or "History".) 578 To "Preserve the Title" of such a section when you modify the 579 Document means that it remains a section "Entitled XYZ" according 580 to this definition. 581 582 The Document may include Warranty Disclaimers next to the notice 583 which states that this License applies to the Document. These 584 Warranty Disclaimers are considered to be included by reference in 585 this License, but only as regards disclaiming warranties: any other 586 implication that these Warranty Disclaimers may have is void and 587 has no effect on the meaning of this License. 588 589 2. VERBATIM COPYING 590 591 You may copy and distribute the Document in any medium, either 592 commercially or noncommercially, provided that this License, the 593 copyright notices, and the license notice saying this License 594 applies to the Document are reproduced in all copies, and that you 595 add no other conditions whatsoever to those of this License. You 596 may not use technical measures to obstruct or control the reading 597 or further copying of the copies you make or distribute. However, 598 you may accept compensation in exchange for copies. If you 599 distribute a large enough number of copies you must also follow 600 the conditions in section 3. 601 602 You may also lend copies, under the same conditions stated above, 603 and you may publicly display copies. 604 605 3. COPYING IN QUANTITY 606 607 If you publish printed copies (or copies in media that commonly 608 have printed covers) of the Document, numbering more than 100, and 609 the Document's license notice requires Cover Texts, you must 610 enclose the copies in covers that carry, clearly and legibly, all 611 these Cover Texts: Front-Cover Texts on the front cover, and 612 Back-Cover Texts on the back cover. Both covers must also clearly 613 and legibly identify you as the publisher of these copies. The 614 front cover must present the full title with all words of the 615 title equally prominent and visible. You may add other material 616 on the covers in addition. Copying with changes limited to the 617 covers, as long as they preserve the title of the Document and 618 satisfy these conditions, can be treated as verbatim copying in 619 other respects. 620 621 If the required texts for either cover are too voluminous to fit 622 legibly, you should put the first ones listed (as many as fit 623 reasonably) on the actual cover, and continue the rest onto 624 adjacent pages. 625 626 If you publish or distribute Opaque copies of the Document 627 numbering more than 100, you must either include a 628 machine-readable Transparent copy along with each Opaque copy, or 629 state in or with each Opaque copy a computer-network location from 630 which the general network-using public has access to download 631 using public-standard network protocols a complete Transparent 632 copy of the Document, free of added material. If you use the 633 latter option, you must take reasonably prudent steps, when you 634 begin distribution of Opaque copies in quantity, to ensure that 635 this Transparent copy will remain thus accessible at the stated 636 location until at least one year after the last time you 637 distribute an Opaque copy (directly or through your agents or 638 retailers) of that edition to the public. 639 640 It is requested, but not required, that you contact the authors of 641 the Document well before redistributing any large number of 642 copies, to give them a chance to provide you with an updated 643 version of the Document. 644 645 4. MODIFICATIONS 646 647 You may copy and distribute a Modified Version of the Document 648 under the conditions of sections 2 and 3 above, provided that you 649 release the Modified Version under precisely this License, with 650 the Modified Version filling the role of the Document, thus 651 licensing distribution and modification of the Modified Version to 652 whoever possesses a copy of it. In addition, you must do these 653 things in the Modified Version: 654 655 A. Use in the Title Page (and on the covers, if any) a title 656 distinct from that of the Document, and from those of 657 previous versions (which should, if there were any, be listed 658 in the History section of the Document). You may use the 659 same title as a previous version if the original publisher of 660 that version gives permission. 661 662 B. List on the Title Page, as authors, one or more persons or 663 entities responsible for authorship of the modifications in 664 the Modified Version, together with at least five of the 665 principal authors of the Document (all of its principal 666 authors, if it has fewer than five), unless they release you 667 from this requirement. 668 669 C. State on the Title page the name of the publisher of the 670 Modified Version, as the publisher. 671 672 D. Preserve all the copyright notices of the Document. 673 674 E. Add an appropriate copyright notice for your modifications 675 adjacent to the other copyright notices. 676 677 F. Include, immediately after the copyright notices, a license 678 notice giving the public permission to use the Modified 679 Version under the terms of this License, in the form shown in 680 the Addendum below. 681 682 G. Preserve in that license notice the full lists of Invariant 683 Sections and required Cover Texts given in the Document's 684 license notice. 685 686 H. Include an unaltered copy of this License. 687 688 I. Preserve the section Entitled "History", Preserve its Title, 689 and add to it an item stating at least the title, year, new 690 authors, and publisher of the Modified Version as given on 691 the Title Page. If there is no section Entitled "History" in 692 the Document, create one stating the title, year, authors, 693 and publisher of the Document as given on its Title Page, 694 then add an item describing the Modified Version as stated in 695 the previous sentence. 696 697 J. Preserve the network location, if any, given in the Document 698 for public access to a Transparent copy of the Document, and 699 likewise the network locations given in the Document for 700 previous versions it was based on. These may be placed in 701 the "History" section. You may omit a network location for a 702 work that was published at least four years before the 703 Document itself, or if the original publisher of the version 704 it refers to gives permission. 705 706 K. For any section Entitled "Acknowledgements" or "Dedications", 707 Preserve the Title of the section, and preserve in the 708 section all the substance and tone of each of the contributor 709 acknowledgements and/or dedications given therein. 710 711 L. Preserve all the Invariant Sections of the Document, 712 unaltered in their text and in their titles. Section numbers 713 or the equivalent are not considered part of the section 714 titles. 715 716 M. Delete any section Entitled "Endorsements". Such a section 717 may not be included in the Modified Version. 718 719 N. Do not retitle any existing section to be Entitled 720 "Endorsements" or to conflict in title with any Invariant 721 Section. 722 723 O. Preserve any Warranty Disclaimers. 724 725 If the Modified Version includes new front-matter sections or 726 appendices that qualify as Secondary Sections and contain no 727 material copied from the Document, you may at your option 728 designate some or all of these sections as invariant. To do this, 729 add their titles to the list of Invariant Sections in the Modified 730 Version's license notice. These titles must be distinct from any 731 other section titles. 732 733 You may add a section Entitled "Endorsements", provided it contains 734 nothing but endorsements of your Modified Version by various 735 parties--for example, statements of peer review or that the text 736 has been approved by an organization as the authoritative 737 definition of a standard. 738 739 You may add a passage of up to five words as a Front-Cover Text, 740 and a passage of up to 25 words as a Back-Cover Text, to the end 741 of the list of Cover Texts in the Modified Version. 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COMBINING DOCUMENTS 755 756 You may combine the Document with other documents released under 757 this License, under the terms defined in section 4 above for 758 modified versions, provided that you include in the combination 759 all of the Invariant Sections of all of the original documents, 760 unmodified, and list them all as Invariant Sections of your 761 combined work in its license notice, and that you preserve all 762 their Warranty Disclaimers. 763 764 The combined work need only contain one copy of this License, and 765 multiple identical Invariant Sections may be replaced with a single 766 copy. If there are multiple Invariant Sections with the same name 767 but different contents, make the title of each such section unique 768 by adding at the end of it, in parentheses, the name of the 769 original author or publisher of that section if known, or else a 770 unique number. Make the same adjustment to the section titles in 771 the list of Invariant Sections in the license notice of the 772 combined work. 773 774 In the combination, you must combine any sections Entitled 775 "History" in the various original documents, forming one section 776 Entitled "History"; likewise combine any sections Entitled 777 "Acknowledgements", and any sections Entitled "Dedications". You 778 must delete all sections Entitled "Endorsements." 779 780 6. COLLECTIONS OF DOCUMENTS 781 782 You may make a collection consisting of the Document and other 783 documents released under this License, and replace the individual 784 copies of this License in the various documents with a single copy 785 that is included in the collection, provided that you follow the 786 rules of this License for verbatim copying of each of the 787 documents in all other respects. 788 789 You may extract a single document from such a collection, and 790 distribute it individually under this License, provided you insert 791 a copy of this License into the extracted document, and follow 792 this License in all other respects regarding verbatim copying of 793 that document. 794 795 7. AGGREGATION WITH INDEPENDENT WORKS 796 797 A compilation of the Document or its derivatives with other 798 separate and independent documents or works, in or on a volume of 799 a storage or distribution medium, is called an "aggregate" if the 800 copyright resulting from the compilation is not used to limit the 801 legal rights of the compilation's users beyond what the individual 802 works permit. When the Document is included in an aggregate, this 803 License does not apply to the other works in the aggregate which 804 are not themselves derivative works of the Document. 805 806 If the Cover Text requirement of section 3 is applicable to these 807 copies of the Document, then if the Document is less than one half 808 of the entire aggregate, the Document's Cover Texts may be placed 809 on covers that bracket the Document within the aggregate, or the 810 electronic equivalent of covers if the Document is in electronic 811 form. Otherwise they must appear on printed covers that bracket 812 the whole aggregate. 813 814 8. TRANSLATION 815 816 Translation is considered a kind of modification, so you may 817 distribute translations of the Document under the terms of section 818 4. Replacing Invariant Sections with translations requires special 819 permission from their copyright holders, but you may include 820 translations of some or all Invariant Sections in addition to the 821 original versions of these Invariant Sections. You may include a 822 translation of this License, and all the license notices in the 823 Document, and any Warranty Disclaimers, provided that you also 824 include the original English version of this License and the 825 original versions of those notices and disclaimers. In case of a 826 disagreement between the translation and the original version of 827 this License or a notice or disclaimer, the original version will 828 prevail. 829 830 If a section in the Document is Entitled "Acknowledgements", 831 "Dedications", or "History", the requirement (section 4) to 832 Preserve its Title (section 1) will typically require changing the 833 actual title. 834 835 9. TERMINATION 836 837 You may not copy, modify, sublicense, or distribute the Document 838 except as expressly provided for under this License. Any other 839 attempt to copy, modify, sublicense or distribute the Document is 840 void, and will automatically terminate your rights under this 841 License. However, parties who have received copies, or rights, 842 from you under this License will not have their licenses 843 terminated so long as such parties remain in full compliance. 844 845 10. FUTURE REVISIONS OF THIS LICENSE 846 847 The Free Software Foundation may publish new, revised versions of 848 the GNU Free Documentation License from time to time. Such new 849 versions will be similar in spirit to the present version, but may 850 differ in detail to address new problems or concerns. See 851 `http://www.gnu.org/copyleft/'. 852 853 Each version of the License is given a distinguishing version 854 number. If the Document specifies that a particular numbered 855 version of this License "or any later version" applies to it, you 856 have the option of following the terms and conditions either of 857 that specified version or of any later version that has been 858 published (not as a draft) by the Free Software Foundation. If 859 the Document does not specify a version number of this License, 860 you may choose any version ever published (not as a draft) by the 861 Free Software Foundation. 862 863ADDENDUM: How to use this License for your documents 864==================================================== 865 866To use this License in a document you have written, include a copy of 867the License in the document and put the following copyright and license 868notices just after the title page: 869 870 Copyright (C) YEAR YOUR NAME. 871 Permission is granted to copy, distribute and/or modify this document 872 under the terms of the GNU Free Documentation License, Version 1.2 873 or any later version published by the Free Software Foundation; 874 with no Invariant Sections, no Front-Cover Texts, and no Back-Cover 875 Texts. A copy of the license is included in the section entitled ``GNU 876 Free Documentation License''. 877 878 If you have Invariant Sections, Front-Cover Texts and Back-Cover 879Texts, replace the "with...Texts." line with this: 880 881 with the Invariant Sections being LIST THEIR TITLES, with 882 the Front-Cover Texts being LIST, and with the Back-Cover Texts 883 being LIST. 884 885 If you have Invariant Sections without Cover Texts, or some other 886combination of the three, merge those two alternatives to suit the 887situation. 888 889 If your document contains nontrivial examples of program code, we 890recommend releasing these examples in parallel under your choice of 891free software license, such as the GNU General Public License, to 892permit their use in free software. 893 894 895File: gcj.info, Node: Invoking gcj, Next: Compatibility, Prev: GNU Free Documentation License, Up: Top 896 8971 Invoking gcj 898************** 899 900As `gcj' is just another front end to `gcc', it supports many of the 901same options as gcc. *Note Option Summary: (gcc)Option Summary. This 902manual only documents the options specific to `gcj'. 903 904* Menu: 905 906* Input and output files:: 907* Input Options:: How gcj finds files 908* Encodings:: Options controlling source file encoding 909* Warnings:: Options controlling warnings specific to gcj 910* Linking:: Options for making an executable 911* Code Generation:: Options controlling the output of gcj 912* Configure-time Options:: Options you won't use 913 914 915File: gcj.info, Node: Input and output files, Next: Input Options, Up: Invoking gcj 916 9171.1 Input and output files 918========================== 919 920A `gcj' command is like a `gcc' command, in that it consists of a 921number of options and file names. The following kinds of input file 922names are supported: 923 924`FILE.java' 925 Java source files. 926 927`FILE.class' 928 Java bytecode files. 929 930`FILE.zip' 931`FILE.jar' 932 An archive containing one or more `.class' files, all of which are 933 compiled. The archive may be compressed. Files in an archive 934 which don't end with `.class' are treated as resource files; they 935 are compiled into the resulting object file as `core:' URLs. 936 937`@FILE' 938 A file containing a whitespace-separated list of input file names. 939 (Currently, these must all be `.java' source files, but that may 940 change.) Each named file is compiled, just as if it had been on 941 the command line. 942 943`LIBRARY.a' 944`LIBRARY.so' 945`-lLIBNAME' 946 Libraries to use when linking. See the `gcc' manual. 947 948 You can specify more than one input file on the `gcj' command line, 949in which case they will all be compiled. If you specify a `-o FILENAME' 950option, all the input files will be compiled together, producing a 951single output file, named FILENAME. This is allowed even when using 952`-S' or `-c', but not when using `-C' or `--resource'. (This is an 953extension beyond the what plain `gcc' allows.) (If more than one input 954file is specified, all must currently be `.java' files, though we hope 955to fix this.) 956 957 958File: gcj.info, Node: Input Options, Next: Encodings, Prev: Input and output files, Up: Invoking gcj 959 9601.2 Input Options 961================= 962 963`gcj' has options to control where it looks to find files it needs. 964For instance, `gcj' might need to load a class that is referenced by 965the file it has been asked to compile. Like other compilers for the 966Java language, `gcj' has a notion of a "class path". There are several 967options and environment variables which can be used to manipulate the 968class path. When `gcj' looks for a given class, it searches the class 969path looking for matching `.class' or `.java' file. `gcj' comes with a 970built-in class path which points at the installed `libgcj.jar', a file 971which contains all the standard classes. 972 973 In the below, a directory or path component can refer either to an 974actual directory on the filesystem, or to a `.zip' or `.jar' file, 975which `gcj' will search as if it is a directory. 976 977`-IDIR' 978 All directories specified by `-I' are kept in order and prepended 979 to the class path constructed from all the other options. Unless 980 compatibility with tools like `javac' is important, we recommend 981 always using `-I' instead of the other options for manipulating the 982 class path. 983 984`--classpath=PATH' 985 This sets the class path to PATH, a colon-separated list of paths 986 (on Windows-based systems, a semicolon-separate list of paths). 987 This does not override the builtin ("boot") search path. 988 989`--CLASSPATH=PATH' 990 Deprecated synonym for `--classpath'. 991 992`--bootclasspath=PATH' 993 Where to find the standard builtin classes, such as 994 `java.lang.String'. 995 996`--extdirs=PATH' 997 For each directory in the PATH, place the contents of that 998 directory at the end of the class path. 999 1000`CLASSPATH' 1001 This is an environment variable which holds a list of paths. 1002 1003 The final class path is constructed like so: 1004 1005 * First come all directories specified via `-I'. 1006 1007 * If `--classpath' is specified, its value is appended. Otherwise, 1008 if the `CLASSPATH' environment variable is specified, then its 1009 value is appended. Otherwise, the current directory (`"."') is 1010 appended. 1011 1012 * If `--bootclasspath' was specified, append its value. Otherwise, 1013 append the built-in system directory, `libgcj.jar'. 1014 1015 * Finally, if `--extdirs' was specified, append the contents of the 1016 specified directories at the end of the class path. Otherwise, 1017 append the contents of the built-in extdirs at 1018 `$(prefix)/share/java/ext'. 1019 1020 The classfile built by `gcj' for the class `java.lang.Object' (and 1021placed in `libgcj.jar') contains a special zero length attribute 1022`gnu.gcj.gcj-compiled'. The compiler looks for this attribute when 1023loading `java.lang.Object' and will report an error if it isn't found, 1024unless it compiles to bytecode (the option 1025`-fforce-classes-archive-check' can be used to override this behavior 1026in this particular case.) 1027 1028`-fforce-classes-archive-check' 1029 This forces the compiler to always check for the special zero 1030 length attribute `gnu.gcj.gcj-compiled' in `java.lang.Object' and 1031 issue an error if it isn't found. 1032 1033 1034File: gcj.info, Node: Encodings, Next: Warnings, Prev: Input Options, Up: Invoking gcj 1035 10361.3 Encodings 1037============= 1038 1039The Java programming language uses Unicode throughout. In an effort to 1040integrate well with other locales, `gcj' allows `.java' files to be 1041written using almost any encoding. `gcj' knows how to convert these 1042encodings into its internal encoding at compile time. 1043 1044 You can use the `--encoding=NAME' option to specify an encoding (of 1045a particular character set) to use for source files. If this is not 1046specified, the default encoding comes from your current locale. If 1047your host system has insufficient locale support, then `gcj' assumes 1048the default encoding to be the `UTF-8' encoding of Unicode. 1049 1050 To implement `--encoding', `gcj' simply uses the host platform's 1051`iconv' conversion routine. This means that in practice `gcj' is 1052limited by the capabilities of the host platform. 1053 1054 The names allowed for the argument `--encoding' vary from platform 1055to platform (since they are not standardized anywhere). However, `gcj' 1056implements the encoding named `UTF-8' internally, so if you choose to 1057use this for your source files you can be assured that it will work on 1058every host. 1059 1060 1061File: gcj.info, Node: Warnings, Next: Linking, Prev: Encodings, Up: Invoking gcj 1062 10631.4 Warnings 1064============ 1065 1066`gcj' implements several warnings. As with other generic `gcc' 1067warnings, if an option of the form `-Wfoo' enables a warning, then 1068`-Wno-foo' will disable it. Here we've chosen to document the form of 1069the warning which will have an effect - the default being the opposite 1070of what is listed. 1071 1072`-Wredundant-modifiers' 1073 With this flag, `gcj' will warn about redundant modifiers. For 1074 instance, it will warn if an interface method is declared `public'. 1075 1076`-Wextraneous-semicolon' 1077 This causes `gcj' to warn about empty statements. Empty statements 1078 have been deprecated. 1079 1080`-Wno-out-of-date' 1081 This option will cause `gcj' not to warn when a source file is 1082 newer than its matching class file. By default `gcj' will warn 1083 about this. 1084 1085`-Wno-deprecated' 1086 Warn if a deprecated class, method, or field is referred to. 1087 1088`-Wunused' 1089 This is the same as `gcc''s `-Wunused'. 1090 1091`-Wall' 1092 This is the same as `-Wredundant-modifiers -Wextraneous-semicolon 1093 -Wunused'. 1094 1095 1096File: gcj.info, Node: Linking, Next: Code Generation, Prev: Warnings, Up: Invoking gcj 1097 10981.5 Linking 1099=========== 1100 1101To turn a Java application into an executable program, you need to link 1102it with the needed libraries, just as for C or C++. The linker by 1103default looks for a global function named `main'. Since Java does not 1104have global functions, and a collection of Java classes may have more 1105than one class with a `main' method, you need to let the linker know 1106which of those `main' methods it should invoke when starting the 1107application. You can do that in any of these ways: 1108 1109 * Specify the class containing the desired `main' method when you 1110 link the application, using the `--main' flag, described below. 1111 1112 * Link the Java package(s) into a shared library (dll) rather than an 1113 executable. Then invoke the application using the `gij' program, 1114 making sure that `gij' can find the libraries it needs. 1115 1116 * Link the Java packages(s) with the flag `-lgij', which links in 1117 the `main' routine from the `gij' command. This allows you to 1118 select the class whose `main' method you want to run when you run 1119 the application. You can also use other `gij' flags, such as `-D' 1120 flags to set properties. Using the `-lgij' library (rather than 1121 the `gij' program of the previous mechanism) has some advantages: 1122 it is compatible with static linking, and does not require 1123 configuring or installing libraries. 1124 1125 These `gij' options relate to linking an executable: 1126 1127`--main=CLASSNAME' 1128 This option is used when linking to specify the name of the class 1129 whose `main' method should be invoked when the resulting 1130 executable is run. 1131 1132`-DNAME[=VALUE]' 1133 This option can only be used with `--main'. It defines a system 1134 property named NAME with value VALUE. If VALUE is not specified 1135 then it defaults to the empty string. These system properties are 1136 initialized at the program's startup and can be retrieved at 1137 runtime using the `java.lang.System.getProperty' method. 1138 1139`-lgij' 1140 Create an application whose command-line processing is that of the 1141 `gij' command. 1142 1143 This option is an alternative to using `--main'; you cannot use 1144 both. 1145 1146`-static-libgcj' 1147 This option causes linking to be done against a static version of 1148 the libgcj runtime library. This option is only available if 1149 corresponding linker support exists. 1150 1151 *Caution:* Static linking of libgcj may cause essential parts of 1152 libgcj to be omitted. Some parts of libgcj use reflection to load 1153 classes at runtime. Since the linker does not see these 1154 references at link time, it can omit the referred to classes. The 1155 result is usually (but not always) a `ClassNotFoundException' 1156 being thrown at runtime. Caution must be used when using this 1157 option. For more details see: 1158 `http://gcc.gnu.org/wiki/Statically%20linking%20libgcj' 1159 1160 1161File: gcj.info, Node: Code Generation, Next: Configure-time Options, Prev: Linking, Up: Invoking gcj 1162 11631.6 Code Generation 1164=================== 1165 1166In addition to the many `gcc' options controlling code generation, 1167`gcj' has several options specific to itself. 1168 1169`-C' 1170 This option is used to tell `gcj' to generate bytecode (`.class' 1171 files) rather than object code. 1172 1173`--resource RESOURCE-NAME' 1174 This option is used to tell `gcj' to compile the contents of a 1175 given file to object code so it may be accessed at runtime with 1176 the core protocol handler as `core:/RESOURCE-NAME'. Note that 1177 RESOURCE-NAME is the name of the resource as found at runtime; for 1178 instance, it could be used in a call to `ResourceBundle.getBundle'. 1179 The actual file name to be compiled this way must be specified 1180 separately. 1181 1182`-d DIRECTORY' 1183 When used with `-C', this causes all generated `.class' files to 1184 be put in the appropriate subdirectory of DIRECTORY. By default 1185 they will be put in subdirectories of the current working 1186 directory. 1187 1188`-fno-bounds-check' 1189 By default, `gcj' generates code which checks the bounds of all 1190 array indexing operations. With this option, these checks are 1191 omitted, which can improve performance for code that uses arrays 1192 extensively. Note that this can result in unpredictable behavior 1193 if the code in question actually does violate array bounds 1194 constraints. It is safe to use this option if you are sure that 1195 your code will never throw an `ArrayIndexOutOfBoundsException'. 1196 1197`-fno-store-check' 1198 Don't generate array store checks. When storing objects into 1199 arrays, a runtime check is normally generated in order to ensure 1200 that the object is assignment compatible with the component type 1201 of the array (which may not be known at compile-time). With this 1202 option, these checks are omitted. This can improve performance 1203 for code which stores objects into arrays frequently. It is safe 1204 to use this option if you are sure your code will never throw an 1205 `ArrayStoreException'. 1206 1207`-fjni' 1208 With `gcj' there are two options for writing native methods: CNI 1209 and JNI. By default `gcj' assumes you are using CNI. If you are 1210 compiling a class with native methods, and these methods are 1211 implemented using JNI, then you must use `-fjni'. This option 1212 causes `gcj' to generate stubs which will invoke the underlying JNI 1213 methods. 1214 1215`-fno-assert' 1216 Don't recognize the `assert' keyword. This is for compatibility 1217 with older versions of the language specification. 1218 1219`-fno-optimize-static-class-initialization' 1220 When the optimization level is greater or equal to `-O2', `gcj' 1221 will try to optimize the way calls into the runtime are made to 1222 initialize static classes upon their first use (this optimization 1223 isn't carried out if `-C' was specified.) When compiling to native 1224 code, `-fno-optimize-static-class-initialization' will turn this 1225 optimization off, regardless of the optimization level in use. 1226 1227`--disable-assertions[=CLASS-OR-PACKAGE]' 1228 Don't include code for checking assertions in the compiled code. 1229 If `=CLASS-OR-PACKAGE' is missing disables assertion code 1230 generation for all classes, unless overridden by a more specific 1231 `--enable-assertions' flag. If CLASS-OR-PACKAGE is a class name, 1232 only disables generating assertion checks within the named class 1233 or its inner classes. If CLASS-OR-PACKAGE is a package name, 1234 disables generating assertion checks within the named package or a 1235 subpackage. 1236 1237 By default, assertions are enabled when generating class files or 1238 when not optimizing, and disabled when generating optimized 1239 binaries. 1240 1241`--enable-assertions[=CLASS-OR-PACKAGE]' 1242 Generates code to check assertions. The option is perhaps 1243 misnamed, as you still need to turn on assertion checking at 1244 run-time, and we don't support any easy way to do that. So this 1245 flag isn't very useful yet, except to partially override 1246 `--disable-assertions'. 1247 1248`-findirect-dispatch' 1249 `gcj' has a special binary compatibility ABI, which is enabled by 1250 the `-findirect-dispatch' option. In this mode, the code 1251 generated by `gcj' honors the binary compatibility guarantees in 1252 the Java Language Specification, and the resulting object files do 1253 not need to be directly linked against their dependencies. 1254 Instead, all dependencies are looked up at runtime. This allows 1255 free mixing of interpreted and compiled code. 1256 1257 Note that, at present, `-findirect-dispatch' can only be used when 1258 compiling `.class' files. It will not work when compiling from 1259 source. CNI also does not yet work with the binary compatibility 1260 ABI. These restrictions will be lifted in some future release. 1261 1262 However, if you compile CNI code with the standard ABI, you can 1263 call it from code built with the binary compatibility ABI. 1264 1265`-fbootstrap-classes' 1266 This option can be use to tell `libgcj' that the compiled classes 1267 should be loaded by the bootstrap loader, not the system class 1268 loader. By default, if you compile a class and link it into an 1269 executable, it will be treated as if it was loaded using the 1270 system class loader. This is convenient, as it means that things 1271 like `Class.forName()' will search `CLASSPATH' to find the desired 1272 class. 1273 1274`-freduced-reflection' 1275 This option causes the code generated by `gcj' to contain a 1276 reduced amount of the class meta-data used to support runtime 1277 reflection. The cost of this savings is the loss of the ability to 1278 use certain reflection capabilities of the standard Java runtime 1279 environment. When set all meta-data except for that which is 1280 needed to obtain correct runtime semantics is eliminated. 1281 1282 For code that does not use reflection (i.e. the methods in the 1283 `java.lang.reflect' package), `-freduced-reflection' will result 1284 in proper operation with a savings in executable code size. 1285 1286 JNI (`-fjni') and the binary compatibility ABI 1287 (`-findirect-dispatch') do not work properly without full 1288 reflection meta-data. Because of this, it is an error to use 1289 these options with `-freduced-reflection'. 1290 1291 *Caution:* If there is no reflection meta-data, code that uses a 1292 `SecurityManager' may not work properly. Also calling 1293 `Class.forName()' may fail if the calling method has no reflection 1294 meta-data. 1295 1296 1297 1298File: gcj.info, Node: Configure-time Options, Prev: Code Generation, Up: Invoking gcj 1299 13001.7 Configure-time Options 1301========================== 1302 1303Some `gcj' code generations options affect the resulting ABI, and so 1304can only be meaningfully given when `libgcj', the runtime package, is 1305configured. `libgcj' puts the appropriate options from this group into 1306a `spec' file which is read by `gcj'. These options are listed here 1307for completeness; if you are using `libgcj' then you won't want to 1308touch these options. 1309 1310`-fuse-boehm-gc' 1311 This enables the use of the Boehm GC bitmap marking code. In 1312 particular this causes `gcj' to put an object marking descriptor 1313 into each vtable. 1314 1315`-fhash-synchronization' 1316 By default, synchronization data (the data used for `synchronize', 1317 `wait', and `notify') is pointed to by a word in each object. 1318 With this option `gcj' assumes that this information is stored in a 1319 hash table and not in the object itself. 1320 1321`-fuse-divide-subroutine' 1322 On some systems, a library routine is called to perform integer 1323 division. This is required to get exception handling correct when 1324 dividing by zero. 1325 1326`-fcheck-references' 1327 On some systems it's necessary to insert inline checks whenever 1328 accessing an object via a reference. On other systems you won't 1329 need this because null pointer accesses are caught automatically 1330 by the processor. 1331 1332 1333File: gcj.info, Node: Compatibility, Next: Invoking gcjh, Prev: Invoking gcj, Up: Top 1334 13352 Compatibility with the Java Platform 1336************************************** 1337 1338As we believe it is important that the Java platform not be fragmented, 1339`gcj' and `libgcj' try to conform to the relevant Java specifications. 1340However, limited manpower and incomplete and unclear documentation work 1341against us. So, there are caveats to using `gcj'. 1342 1343* Menu: 1344 1345* Limitations:: 1346* Extensions:: 1347 1348 1349File: gcj.info, Node: Limitations, Next: Extensions, Up: Compatibility 1350 13512.1 Standard features not yet supported 1352======================================= 1353 1354This list of compatibility issues is by no means complete. 1355 1356 * `gcj' implements the JDK 1.2 language. It supports inner classes 1357 and the new 1.4 `assert' keyword. It does not yet support the 1358 Java 2 `strictfp' keyword (it recognizes the keyword but ignores 1359 it). 1360 1361 * `libgcj' is largely compatible with the JDK 1.2 libraries. 1362 However, `libgcj' is missing many packages, most notably 1363 `java.awt'. There are also individual missing classes and methods. 1364 We currently do not have a list showing differences between 1365 `libgcj' and the Java 2 platform. 1366 1367 * Sometimes the `libgcj' implementation of a method or class differs 1368 from the JDK implementation. This is not always a bug. Still, if 1369 it affects you, it probably makes sense to report it so that we 1370 can discuss the appropriate response. 1371 1372 * `gcj' does not currently allow for piecemeal replacement of 1373 components within `libgcj'. Unfortunately, programmers often want 1374 to use newer versions of certain packages, such as those provided 1375 by the Apache Software Foundation's Jakarta project. This has 1376 forced us to place the `org.w3c.dom' and `org.xml.sax' packages 1377 into their own libraries, separate from `libgcj'. If you intend to 1378 use these classes, you must link them explicitly with 1379 `-l-org-w3c-dom' and `-l-org-xml-sax'. Future versions of `gcj' 1380 may not have this restriction. 1381 1382 1383File: gcj.info, Node: Extensions, Prev: Limitations, Up: Compatibility 1384 13852.2 Extra features unique to gcj 1386================================ 1387 1388The main feature of `gcj' is that it can compile programs written in 1389the Java programming language to native code. Most extensions that 1390have been added are to facilitate this functionality. 1391 1392 * `gcj' makes it easy and efficient to mix code written in Java and 1393 C++. *Note About CNI::, for more info on how to use this in your 1394 programs. 1395 1396 * When you compile your classes into a shared library using 1397 `-findirect-dispatch' then add them to the system-wide classmap.db 1398 file using `gcj-dbtool', they will be automatically loaded by the 1399 `libgcj' system classloader. This is the new, preferred 1400 classname-to-library resolution mechanism. *Note Invoking 1401 gcj-dbtool::, for more information on using the classmap database. 1402 1403 * The old classname-to-library lookup mechanism is still supported 1404 through the `gnu.gcj.runtime.VMClassLoader.library_control' 1405 property, but it is deprecated and will likely be removed in some 1406 future release. When trying to load a class `gnu.pkg.SomeClass' 1407 the system classloader will first try to load the shared library 1408 `lib-gnu-pkg-SomeClass.so', if that fails to load the class then 1409 it will try to load `lib-gnu-pkg.so' and finally when the class is 1410 still not loaded it will try to load `lib-gnu.so'. Note that all 1411 `.'s will be transformed into `-'s and that searching for inner 1412 classes starts with their outermost outer class. If the class 1413 cannot be found this way the system classloader tries to use the 1414 `libgcj' bytecode interpreter to load the class from the standard 1415 classpath. This process can be controlled to some degree via the 1416 `gnu.gcj.runtime.VMClassLoader.library_control' property; *Note 1417 libgcj Runtime Properties::. 1418 1419 * `libgcj' includes a special `gcjlib' URL type. A URL of this form 1420 is like a `jar' URL, and looks like 1421 `gcjlib:/path/to/shared/library.so!/path/to/resource'. An access 1422 to one of these URLs causes the shared library to be `dlopen()'d, 1423 and then the resource is looked for in that library. These URLs 1424 are most useful when used in conjunction with 1425 `java.net.URLClassLoader'. Note that, due to implementation 1426 limitations, currently any such URL can be accessed by only one 1427 class loader, and libraries are never unloaded. This means some 1428 care must be exercised to make sure that a `gcjlib' URL is not 1429 accessed by more than one class loader at once. In a future 1430 release this limitation will be lifted, and such libraries will be 1431 mapped privately. 1432 1433 * A program compiled by `gcj' will examine the `GCJ_PROPERTIES' 1434 environment variable and change its behavior in some ways. In 1435 particular `GCJ_PROPERTIES' holds a list of assignments to global 1436 properties, such as would be set with the `-D' option to `java'. 1437 For instance, `java.compiler=gcj' is a valid (but currently 1438 meaningless) setting. 1439 1440 1441 1442File: gcj.info, Node: Invoking gcjh, Next: Invoking gjnih, Prev: Compatibility, Up: Top 1443 14443 Invoking gcjh 1445*************** 1446 1447The `gcjh' program is used to generate header files from class files. 1448It can generate both CNI and JNI header files, as well as stub 1449implementation files which can be used as a basis for implementing the 1450required native methods. 1451 1452`-stubs' 1453 This causes `gcjh' to generate stub files instead of header files. 1454 By default the stub file will be named after the class, with a 1455 suffix of `.cc'. In JNI mode, the default output file will have 1456 the suffix `.c'. 1457 1458`-jni' 1459 This tells `gcjh' to generate a JNI header or stub. By default, 1460 CNI headers are generated. 1461 1462`-force' 1463 This option forces `gcjh' to write the output file. 1464 1465`-old' 1466 This option is accepted but ignored for compatibility. 1467 1468`-trace' 1469 This option is accepted but ignored for compatibility. 1470 1471`-J OPTION' 1472 This option is accepted but ignored for compatibility. 1473 1474`-add TEXT' 1475 Inserts TEXT into the class body. This is ignored in JNI mode. 1476 1477`-append TEXT' 1478 Inserts TEXT into the header file after the class declaration. 1479 This is ignored in JNI mode. 1480 1481`-friend TEXT' 1482 Inserts TEXT into the class as a `friend' declaration. This is 1483 ignored in JNI mode. 1484 1485`-prepend TEXT' 1486 Inserts TEXT into the header file before the class declaration. 1487 This is ignored in JNI mode. 1488 1489`--classpath=PATH' 1490`--CLASSPATH=PATH' 1491`--bootclasspath=PATH' 1492`-IDIRECTORY' 1493`-d DIRECTORY' 1494`-o FILE' 1495 These options are all identical to the corresponding `gcj' options. 1496 1497`-o FILE' 1498 Sets the output file name. This cannot be used if there is more 1499 than one class on the command line. 1500 1501`-td DIRECTORY' 1502 Sets the name of the directory to use for temporary files. 1503 1504`-M' 1505 Print all dependencies to stdout; suppress ordinary output. 1506 1507`-MM' 1508 Print non-system dependencies to stdout; suppress ordinary output. 1509 1510`-MD' 1511 Print all dependencies to stdout. 1512 1513`-MMD' 1514 Print non-system dependencies to stdout. 1515 1516`--help' 1517 Print help about `gcjh' and exit. No further processing is done. 1518 1519`--version' 1520 Print version information for `gcjh' and exit. No further 1521 processing is done. 1522 1523`-v, --verbose' 1524 Print extra information while running. 1525 1526 All remaining options are considered to be names of classes. 1527 1528 1529File: gcj.info, Node: Invoking gjnih, Next: Invoking jv-scan, Prev: Invoking gcjh, Up: Top 1530 15314 Invoking gjnih 1532**************** 1533 1534The `gjnih' program is used to generate JNI header files from class 1535files. Running it is equivalent to running `gcjh -jni'. 1536 1537`-stubs' 1538 This causes `gjnih' to generate stub files instead of header files. 1539 By default the stub file will be named after the class, with a 1540 suffix of `.c'. 1541 1542`-jni' 1543 This option specifies the default behavior which is to generate a 1544 JNI header or stub. 1545 1546`-force' 1547 This option forces `gjnih' to write the output file. 1548 1549`-old' 1550 This option is accepted but ignored for compatibility. 1551 1552`-trace' 1553 This option is accepted but ignored for compatibility. 1554 1555`-J OPTION' 1556 This option is accepted but ignored for compatibility. 1557 1558`-add TEXT' 1559 Inserts TEXT into the class body. This is ignored in by `gjnih'. 1560 1561`-append TEXT' 1562 Inserts TEXT into the header file after the class declaration. 1563 This is ignored in by `gjnih'. 1564 1565`-friend TEXT' 1566 Inserts TEXT into the class as a `friend' declaration. This is 1567 ignored by `gjnih'. 1568 1569`-prepend TEXT' 1570 Inserts TEXT into the header file before the class declaration. 1571 This is ignored in by `gjnih'. 1572 1573`--classpath=PATH' 1574`--CLASSPATH=PATH' 1575`--bootclasspath=PATH' 1576`-IDIRECTORY' 1577`-d DIRECTORY' 1578`-o FILE' 1579 These options are all identical to the corresponding `gcj' options. 1580 1581`-o FILE' 1582 Sets the output file name. This cannot be used if there is more 1583 than one class on the command line. 1584 1585`-td DIRECTORY' 1586 Sets the name of the directory to use for temporary files. 1587 1588`-M' 1589 Print all dependencies to stdout; suppress ordinary output. 1590 1591`-MM' 1592 Print non-system dependencies to stdout; suppress ordinary output. 1593 1594`-MD' 1595 Print all dependencies to stdout. 1596 1597`-MMD' 1598 Print non-system dependencies to stdout. 1599 1600`--help' 1601 Print help about `gjnih' and exit. No further processing is done. 1602 1603`--version' 1604 Print version information for `gjnih' and exit. No further 1605 processing is done. 1606 1607`-v, --verbose' 1608 Print extra information while running. 1609 1610 All remaining options are considered to be names of classes. 1611 1612 1613File: gcj.info, Node: Invoking jv-scan, Next: Invoking jcf-dump, Prev: Invoking gjnih, Up: Top 1614 16155 Invoking jv-scan 1616****************** 1617 1618The `jv-scan' program can be used to print information about a Java 1619source file (`.java' file). 1620 1621`--no-assert' 1622 Don't recognize the `assert' keyword, for backwards compatibility 1623 with older versions of the language specification. 1624 1625`--complexity' 1626 This prints a complexity measure, related to cyclomatic 1627 complexity, for each input file. 1628 1629`--encoding=NAME' 1630 This works like the corresponding `gcj' option. 1631 1632`--print-main' 1633 This prints the name of the class in this file containing a `main' 1634 method. 1635 1636`--list-class' 1637 This lists the names of all classes defined in the input files. 1638 1639`--list-filename' 1640 If `--list-class' is given, this option causes `jv-scan' to also 1641 print the name of the file in which each class was found. 1642 1643`-o FILE' 1644 Print output to the named file. 1645 1646`--help' 1647 Print help, then exit. 1648 1649`--version' 1650 Print version number, then exit. 1651 1652 1653File: gcj.info, Node: Invoking jcf-dump, Next: Invoking gij, Prev: Invoking jv-scan, Up: Top 1654 16556 Invoking jcf-dump 1656******************* 1657 1658This is a class file examiner, similar to `javap'. It will print 1659information about a number of classes, which are specified by class name 1660or file name. 1661 1662`-c' 1663 Disassemble method bodies. By default method bodies are not 1664 printed. 1665 1666`--print-constants' 1667 Print the constant pool. When printing a reference to a constant 1668 also print its index in the constant pool. 1669 1670`--javap' 1671 Generate output in `javap' format. The implementation of this 1672 feature is very incomplete. 1673 1674`--classpath=PATH' 1675`--CLASSPATH=PATH' 1676`-IDIRECTORY' 1677`-o FILE' 1678 These options as the same as the corresponding `gcj' options. 1679 1680`--help' 1681 Print help, then exit. 1682 1683`--version' 1684 Print version number, then exit. 1685 1686`-v, --verbose' 1687 Print extra information while running. Implies 1688 `--print-constants'. 1689 1690 1691File: gcj.info, Node: Invoking gij, Next: Invoking gcj-dbtool, Prev: Invoking jcf-dump, Up: Top 1692 16937 Invoking gij 1694************** 1695 1696`gij' is a Java bytecode interpreter included with `libgcj'. `gij' is 1697not available on every platform; porting it requires a small amount of 1698assembly programming which has not been done for all the targets 1699supported by `gcj'. 1700 1701 The primary argument to `gij' is the name of a class or, with 1702`-jar', a jar file. Options before this argument are interpreted by 1703`gij'; remaining options are passed to the interpreted program. 1704 1705 If a class name is specified and this class does not have a `main' 1706method with the appropriate signature (a `static void' method with a 1707`String[]' as its sole argument), then `gij' will print an error and 1708exit. 1709 1710 If a jar file is specified then `gij' will use information in it to 1711determine which class' `main' method will be invoked. 1712 1713 `gij' will invoke the `main' method with all the remaining 1714command-line options. 1715 1716 Note that `gij' is not limited to interpreting code. Because 1717`libgcj' includes a class loader which can dynamically load shared 1718objects, it is possible to give `gij' the name of a class which has 1719been compiled and put into a shared library on the class path. 1720 1721`-cp PATH' 1722`-classpath PATH' 1723 Set the initial class path. The class path is used for finding 1724 class and resource files. If specified, this option overrides the 1725 `CLASSPATH' environment variable. Note that this option is 1726 ignored if `-jar' is used. 1727 1728`-DNAME[=VALUE]' 1729 This defines a system property named NAME with value VALUE. If 1730 VALUE is not specified then it defaults to the empty string. 1731 These system properties are initialized at the program's startup 1732 and can be retrieved at runtime using the 1733 `java.lang.System.getProperty' method. 1734 1735`-ms=NUMBER' 1736 Equivalent to `-Xms'. 1737 1738`-mx=NUMBER' 1739 Equivalent to `-Xmx'. 1740 1741`-noverify' 1742 Do not verify compliance of bytecode with the VM specification. In 1743 addition, this option disables type verification which is 1744 otherwise performed on BC-ABI compiled code. 1745 1746`-X' 1747`-XARGUMENT' 1748 Supplying `-X' by itself will cause `gij' to list all the 1749 supported `-X' options. Currently these options are supported: 1750 1751 `-XmsSIZE' 1752 Set the initial heap size. 1753 1754 `-XmxSIZE' 1755 Set the maximum heap size. 1756 1757 `-XssSIZE' 1758 Set the thread stack size. 1759 1760 Unrecognized `-X' options are ignored, for compatibility with 1761 other runtimes. 1762 1763`-jar' 1764 This indicates that the name passed to `gij' should be interpreted 1765 as the name of a jar file, not a class. 1766 1767`--help' 1768`-?' 1769 Print help, then exit. 1770 1771`--showversion' 1772 Print version number and continue. 1773 1774`--fullversion' 1775 Print detailed version information, then exit. 1776 1777`--version' 1778 Print version number, then exit. 1779 1780`-verbose' 1781`-verbose:class' 1782 Each time a class is initialized, print a short message on 1783 standard error. 1784 1785 `gij' also recognizes and ignores the following options, for 1786compatibility with existing application launch scripts: `-client', 1787`-server', `-hotspot', `-jrockit', `-agentlib', `-agentpath', `-debug', 1788`-d32', `-d64', `-javaagent', `-noclassgc', `-verify', and 1789`-verifyremote'. 1790 1791 1792File: gcj.info, Node: Invoking gcj-dbtool, Next: Invoking jv-convert, Prev: Invoking gij, Up: Top 1793 17948 Invoking gcj-dbtool. 1795********************** 1796 1797`gcj-dbtool' is a tool for creating and manipulating class file mapping 1798databases. `libgcj' can use these databases to find a shared library 1799corresponding to the bytecode representation of a class. This 1800functionality is useful for ahead-of-time compilation of a program that 1801has no knowledge of `gcj'. 1802 1803 `gcj-dbtool' works best if all the jar files added to it are 1804compiled using `-findirect-dispatch'. 1805 1806 Note that `gcj-dbtool' is currently available as "preview 1807technology". We believe it is a reasonable way to allow 1808application-transparent ahead-of-time compilation, but this is an 1809unexplored area. We welcome your comments. 1810 1811`-n DBFILE [SIZE]' 1812 This creates a new database. Currently, databases cannot be 1813 resized; you can choose a larger initial size if desired. The 1814 default size is 32,749. 1815 1816`-a DBFILE JARFILE LIB' 1817`-f DBFILE JARFILE LIB' 1818 This adds a jar file to the database. For each class file in the 1819 jar, a cryptographic signature of the bytecode representation of 1820 the class is recorded in the database. At runtime, a class is 1821 looked up by its signature and the compiled form of the class is 1822 looked for in the corresponding shared library. The `-a' option 1823 will verify that LIB exists before adding it to the database; `-f' 1824 skips this check. 1825 1826`[`-'][`-0'] -m DBFILE DBFILE,[DBFILE]' 1827 Merge a number of databases. The output database overwrites any 1828 existing database. To add databases into an existing database, 1829 include the destination in the list of sources. 1830 1831 If `-' or `-0' are used, the list of files to read is taken from 1832 standard input instead of the command line. For `-0', Input 1833 filenames are terminated by a null character instead of by 1834 whitespace. Useful when arguments might contain white space. The 1835 GNU find -print0 option produces input suitable for this mode. 1836 1837`-t DBFILE' 1838 Test a database. 1839 1840`-l DBFILE' 1841 List the contents of a database. 1842 1843`-p' 1844 Print the name of the default database. If there is no default 1845 database, this prints a blank line. If LIBDIR is specified, use 1846 it instead of the default library directory component of the 1847 database name. 1848 1849`--help' 1850 Print a help message, then exit. 1851 1852`--version' 1853`-v' 1854 Print version information, then exit. 1855 1856 1857 1858File: gcj.info, Node: Invoking jv-convert, Next: Invoking grmic, Prev: Invoking gcj-dbtool, Up: Top 1859 18609 Invoking jv-convert 1861********************* 1862 1863`jv-convert' [`OPTION'] ... [INPUTFILE [OUTPUTFILE]] 1864 1865 `jv-convert' is a utility included with `libgcj' which converts a 1866file from one encoding to another. It is similar to the Unix `iconv' 1867utility. 1868 1869 The encodings supported by `jv-convert' are platform-dependent. 1870Currently there is no way to get a list of all supported encodings. 1871 1872`--encoding NAME' 1873`--from NAME' 1874 Use NAME as the input encoding. The default is the current 1875 locale's encoding. 1876 1877`--to NAME' 1878 Use NAME as the output encoding. The default is the `JavaSrc' 1879 encoding; this is ASCII with `\u' escapes for non-ASCII characters. 1880 1881`-i FILE' 1882 Read from FILE. The default is to read from standard input. 1883 1884`-o FILE' 1885 Write to FILE. The default is to write to standard output. 1886 1887`--reverse' 1888 Swap the input and output encodings. 1889 1890`--help' 1891 Print a help message, then exit. 1892 1893`--version' 1894 Print version information, then exit. 1895 1896 1897File: gcj.info, Node: Invoking grmic, Next: Invoking grmiregistry, Prev: Invoking jv-convert, Up: Top 1898 189910 Invoking grmic 1900***************** 1901 1902`grmic' [`OPTION'] ... CLASS ... 1903 1904 `grmic' is a utility included with `libgcj' which generates stubs 1905for remote objects. 1906 1907 Note that this program isn't yet fully compatible with the JDK 1908`grmic'. Some options, such as `-classpath', are recognized but 1909currently ignored. We have left these options undocumented for now. 1910 1911 Long options can also be given with a GNU-style leading `--'. For 1912instance, `--help' is accepted. 1913 1914`-keep' 1915`-keepgenerated' 1916 By default, `grmic' deletes intermediate files. Either of these 1917 options causes it not to delete such files. 1918 1919`-v1.1' 1920 Cause `grmic' to create stubs and skeletons for the 1.1 protocol 1921 version. 1922 1923`-vcompat' 1924 Cause `grmic' to create stubs and skeletons compatible with both 1925 the 1.1 and 1.2 protocol versions. This is the default. 1926 1927`-v1.2' 1928 Cause `grmic' to create stubs and skeletons for the 1.2 protocol 1929 version. 1930 1931`-nocompile' 1932 Don't compile the generated files. 1933 1934`-verbose' 1935 Print information about what `grmic' is doing. 1936 1937`-d DIRECTORY' 1938 Put output files in DIRECTORY. By default the files are put in 1939 the current working directory. 1940 1941`-help' 1942 Print a help message, then exit. 1943 1944`-version' 1945 Print version information, then exit. 1946 1947 1948File: gcj.info, Node: Invoking grmiregistry, Next: About CNI, Prev: Invoking grmic, Up: Top 1949 195011 Invoking grmiregistry 1951************************ 1952 1953`grmic' [`OPTION'] ... [PORT] 1954 1955 `grmiregistry' starts a remote object registry on the current host. 1956If no port number is specified, then port 1099 is used. 1957 1958`--help' 1959 Print a help message, then exit. 1960 1961`--version' 1962 Print version information, then exit. 1963 1964 1965File: gcj.info, Node: About CNI, Next: System properties, Prev: Invoking grmiregistry, Up: Top 1966 196712 About CNI 1968************ 1969 1970This documents CNI, the Compiled Native Interface, which is is a 1971convenient way to write Java native methods using C++. This is a more 1972efficient, more convenient, but less portable alternative to the 1973standard JNI (Java Native Interface). 1974 1975* Menu: 1976 1977* Basic concepts:: Introduction to using CNI. 1978* Packages:: How packages are mapped to C++. 1979* Primitive types:: Handling primitive Java types in C++. 1980* Reference types:: Handling Java reference types in C++. 1981* Interfaces:: How Java interfaces map to C++. 1982* Objects and Classes:: C++ and Java classes. 1983* Class Initialization:: How objects are initialized. 1984* Object allocation:: How to create Java objects in C++. 1985* Memory allocation:: How to allocate and free memory. 1986* Arrays:: Dealing with Java arrays in C++. 1987* Methods:: Java methods in C++. 1988* Strings:: Information about Java Strings. 1989* Mixing with C++:: How CNI can interoperate with C++. 1990* Exception Handling:: How exceptions are handled. 1991* Synchronization:: Synchronizing between Java and C++. 1992* Invocation:: Starting the Java runtime from C++. 1993* Reflection:: Using reflection from C++. 1994 1995 1996File: gcj.info, Node: Basic concepts, Next: Packages, Up: About CNI 1997 199812.1 Basic concepts 1999=================== 2000 2001In terms of languages features, Java is mostly a subset of C++. Java 2002has a few important extensions, plus a powerful standard class library, 2003but on the whole that does not change the basic similarity. Java is a 2004hybrid object-oriented language, with a few native types, in addition 2005to class types. It is class-based, where a class may have static as 2006well as per-object fields, and static as well as instance methods. 2007Non-static methods may be virtual, and may be overloaded. Overloading 2008is resolved at compile time by matching the actual argument types 2009against the parameter types. Virtual methods are implemented using 2010indirect calls through a dispatch table (virtual function table). 2011Objects are allocated on the heap, and initialized using a constructor 2012method. Classes are organized in a package hierarchy. 2013 2014 All of the listed attributes are also true of C++, though C++ has 2015extra features (for example in C++ objects may be allocated not just on 2016the heap, but also statically or in a local stack frame). Because 2017`gcj' uses the same compiler technology as G++ (the GNU C++ compiler), 2018it is possible to make the intersection of the two languages use the 2019same ABI (object representation and calling conventions). The key idea 2020in CNI is that Java objects are C++ objects, and all Java classes are 2021C++ classes (but not the other way around). So the most important task 2022in integrating Java and C++ is to remove gratuitous incompatibilities. 2023 2024 You write CNI code as a regular C++ source file. (You do have to use 2025a Java/CNI-aware C++ compiler, specifically a recent version of G++.) 2026 2027A CNI C++ source file must have: 2028 2029 #include <gcj/cni.h> 2030 2031and then must include one header file for each Java class it uses, e.g.: 2032 2033 #include <java/lang/Character.h> 2034 #include <java/util/Date.h> 2035 #include <java/lang/IndexOutOfBoundsException.h> 2036 2037These header files are automatically generated by `gcjh'. 2038 2039 CNI provides some functions and macros to make using Java objects and 2040primitive types from C++ easier. In general, these CNI functions and 2041macros start with the `Jv' prefix, for example the function 2042`JvNewObjectArray'. This convention is used to avoid conflicts with 2043other libraries. Internal functions in CNI start with the prefix 2044`_Jv_'. You should not call these; if you find a need to, let us know 2045and we will try to come up with an alternate solution. 2046 204712.1.1 Limitations 2048------------------ 2049 2050Whilst a Java class is just a C++ class that doesn't mean that you are 2051freed from the shackles of Java, a CNI C++ class must adhere to the 2052rules of the Java programming language. 2053 2054 For example: it is not possible to declare a method in a CNI class 2055that will take a C string (`char*') as an argument, or to declare a 2056member variable of some non-Java datatype. 2057 2058 2059File: gcj.info, Node: Packages, Next: Primitive types, Prev: Basic concepts, Up: About CNI 2060 206112.2 Packages 2062============= 2063 2064The only global names in Java are class names, and packages. A 2065"package" can contain zero or more classes, and also zero or more 2066sub-packages. Every class belongs to either an unnamed package or a 2067package that has a hierarchical and globally unique name. 2068 2069 A Java package is mapped to a C++ "namespace". The Java class 2070`java.lang.String' is in the package `java.lang', which is a 2071sub-package of `java'. The C++ equivalent is the class 2072`java::lang::String', which is in the namespace `java::lang' which is 2073in the namespace `java'. 2074 2075Here is how you could express this: 2076 2077 (// Declare the class(es), possibly in a header file: 2078 namespace java { 2079 namespace lang { 2080 class Object; 2081 class String; 2082 ... 2083 } 2084 } 2085 2086 class java::lang::String : public java::lang::Object 2087 { 2088 ... 2089 }; 2090 2091The `gcjh' tool automatically generates the necessary namespace 2092declarations. 2093 209412.2.1 Leaving out package names 2095-------------------------------- 2096 2097Always using the fully-qualified name of a java class can be tiresomely 2098verbose. Using the full qualified name also ties the code to a single 2099package making code changes necessary should the class move from one 2100package to another. The Java `package' declaration specifies that the 2101following class declarations are in the named package, without having 2102to explicitly name the full package qualifiers. The `package' 2103declaration can be followed by zero or more `import' declarations, which 2104allows either a single class or all the classes in a package to be 2105named by a simple identifier. C++ provides something similar with the 2106`using' declaration and directive. 2107 2108In Java: 2109 2110 import PACKAGE-NAME.CLASS-NAME; 2111 2112allows the program text to refer to CLASS-NAME as a shorthand for the 2113fully qualified name: `PACKAGE-NAME.CLASS-NAME'. 2114 2115To achieve the same effect C++, you have to do this: 2116 2117 using PACKAGE-NAME::CLASS-NAME; 2118 2119Java can also cause imports on demand, like this: 2120 2121 import PACKAGE-NAME.*; 2122 2123Doing this allows any class from the package PACKAGE-NAME to be 2124referred to only by its class-name within the program text. 2125 2126The same effect can be achieved in C++ like this: 2127 2128 using namespace PACKAGE-NAME; 2129 2130 2131File: gcj.info, Node: Primitive types, Next: Reference types, Prev: Packages, Up: About CNI 2132 213312.3 Primitive types 2134==================== 2135 2136Java provides 8 "primitives" types which represent integers, floats, 2137characters and booleans (and also the void type). C++ has its own very 2138similar concrete types. Such types in C++ however are not always 2139implemented in the same way (an int might be 16, 32 or 64 bits for 2140example) so CNI provides a special C++ type for each primitive Java 2141type: 2142 2143*Java type* *C/C++ typename* *Description* 2144`char' `jchar' 16 bit Unicode character 2145`boolean' `jboolean' logical (true or false) values 2146`byte' `jbyte' 8-bit signed integer 2147`short' `jshort' 16 bit signed integer 2148`int' `jint' 32 bit signed integer 2149`long' `jlong' 64 bit signed integer 2150`float' `jfloat' 32 bit IEEE floating point number 2151`double' `jdouble' 64 bit IEEE floating point number 2152`void' `void' no value 2153 2154 When referring to a Java type You should always use these C++ 2155typenames (e.g.: `jint') to avoid disappointment. 2156 215712.3.1 Reference types associated with primitive types 2158------------------------------------------------------ 2159 2160In Java each primitive type has an associated reference type, e.g.: 2161`boolean' has an associated `java.lang.Boolean.TYPE' class. In order 2162to make working with such classes easier GCJ provides the macro 2163`JvPrimClass': 2164 2165 -- macro: JvPrimClass type 2166 Return a pointer to the `Class' object corresponding to the type 2167 supplied. 2168 2169 JvPrimClass(void) => java.lang.Void.TYPE 2170 2171 2172 2173File: gcj.info, Node: Reference types, Next: Interfaces, Prev: Primitive types, Up: About CNI 2174 217512.4 Reference types 2176==================== 2177 2178A Java reference type is treated as a class in C++. Classes and 2179interfaces are handled this way. A Java reference is translated to a 2180C++ pointer, so for instance a Java `java.lang.String' becomes, in C++, 2181`java::lang::String *'. 2182 2183 CNI provides a few built-in typedefs for the most common classes: 2184*Java type* *C++ typename* *Description* 2185`java.lang.Object' `jobject' Object type 2186`java.lang.String' `jstring' String type 2187`java.lang.Class' `jclass' Class type 2188 2189 Every Java class or interface has a corresponding `Class' instance. 2190These can be accessed in CNI via the static `class$' field of a class. 2191The `class$' field is of type `Class' (and not `Class *'), so you will 2192typically take the address of it. 2193 2194 Here is how you can refer to the class of `String', which in Java 2195would be written `String.class': 2196 2197 using namespace java::lang; 2198 doSomething (&String::class$); 2199 2200 2201File: gcj.info, Node: Interfaces, Next: Objects and Classes, Prev: Reference types, Up: About CNI 2202 220312.5 Interfaces 2204=============== 2205 2206A Java class can "implement" zero or more "interfaces", in addition to 2207inheriting from a single base class. 2208 2209 CNI allows CNI code to implement methods of interfaces. You can 2210also call methods through interface references, with some limitations. 2211 2212 CNI doesn't understand interface inheritance at all yet. So, you 2213can only call an interface method when the declared type of the field 2214being called matches the interface which declares that method. The 2215workaround is to cast the interface reference to the right 2216superinterface. 2217 2218 For example if you have: 2219 2220 interface A 2221 { 2222 void a(); 2223 } 2224 2225 interface B extends A 2226 { 2227 void b(); 2228 } 2229 2230 and declare a variable of type `B' in C++, you can't call `a()' 2231unless you cast it to an `A' first. 2232 2233 2234File: gcj.info, Node: Objects and Classes, Next: Class Initialization, Prev: Interfaces, Up: About CNI 2235 223612.6 Objects and Classes 2237======================== 2238 223912.6.1 Classes 2240-------------- 2241 2242All Java classes are derived from `java.lang.Object'. C++ does not 2243have a unique root class, but we use the C++ class `java::lang::Object' 2244as the C++ version of the `java.lang.Object' Java class. All other 2245Java classes are mapped into corresponding C++ classes derived from 2246`java::lang::Object'. 2247 2248 Interface inheritance (the `implements' keyword) is currently not 2249reflected in the C++ mapping. 2250 225112.6.2 Object fields 2252-------------------- 2253 2254Each object contains an object header, followed by the instance fields 2255of the class, in order. The object header consists of a single pointer 2256to a dispatch or virtual function table. (There may be extra fields 2257_in front of_ the object, for example for memory management, but this 2258is invisible to the application, and the reference to the object points 2259to the dispatch table pointer.) 2260 2261 The fields are laid out in the same order, alignment, and size as in 2262C++. Specifically, 8-bit and 16-bit native types (`byte', `short', 2263`char', and `boolean') are _not_ widened to 32 bits. Note that the 2264Java VM does extend 8-bit and 16-bit types to 32 bits when on the VM 2265stack or temporary registers. 2266 2267 If you include the `gcjh'-generated header for a class, you can 2268access fields of Java classes in the _natural_ way. For example, given 2269the following Java class: 2270 2271 public class Int 2272 { 2273 public int i; 2274 public Int (int i) { this.i = i; } 2275 public static Int zero = new Int(0); 2276 } 2277 2278 you can write: 2279 2280 #include <gcj/cni.h>; 2281 #include <Int>; 2282 2283 Int* 2284 mult (Int *p, jint k) 2285 { 2286 if (k == 0) 2287 return Int::zero; // Static member access. 2288 return new Int(p->i * k); 2289 } 2290 229112.6.3 Access specifiers 2292------------------------ 2293 2294CNI does not strictly enforce the Java access specifiers, because Java 2295permissions cannot be directly mapped into C++ permission. Private 2296Java fields and methods are mapped to private C++ fields and methods, 2297but other fields and methods are mapped to public fields and methods. 2298 2299 2300File: gcj.info, Node: Class Initialization, Next: Object allocation, Prev: Objects and Classes, Up: About CNI 2301 230212.7 Class Initialization 2303========================= 2304 2305Java requires that each class be automatically initialized at the time 2306of the first active use. Initializing a class involves initializing 2307the static fields, running code in class initializer methods, and 2308initializing base classes. There may also be some implementation 2309specific actions, such as allocating `String' objects corresponding to 2310string literals in the code. 2311 2312 The GCJ compiler inserts calls to `JvInitClass' at appropriate 2313places to ensure that a class is initialized when required. The C++ 2314compiler does not insert these calls automatically--it is the 2315programmer's responsibility to make sure classes are initialized. 2316However, this is fairly painless because of the conventions assumed by 2317the Java system. 2318 2319 First, `libgcj' will make sure a class is initialized before an 2320instance of that object is created. This is one of the 2321responsibilities of the `new' operation. This is taken care of both in 2322Java code, and in C++ code. When G++ sees a `new' of a Java class, it 2323will call a routine in `libgcj' to allocate the object, and that 2324routine will take care of initializing the class. Note however that 2325this does not happen for Java arrays; you must allocate those using the 2326appropriate CNI function. It follows that you can access an instance 2327field, or call an instance (non-static) method and be safe in the 2328knowledge that the class and all of its base classes have been 2329initialized. 2330 2331 Invoking a static method is also safe. This is because the Java 2332compiler adds code to the start of a static method to make sure the 2333class is initialized. However, the C++ compiler does not add this 2334extra code. Hence, if you write a native static method using CNI, you 2335are responsible for calling `JvInitClass' before doing anything else in 2336the method (unless you are sure it is safe to leave it out). 2337 2338 Accessing a static field also requires the class of the field to be 2339initialized. The Java compiler will generate code to call 2340`JvInitClass' before getting or setting the field. However, the C++ 2341compiler will not generate this extra code, so it is your 2342responsibility to make sure the class is initialized before you access 2343a static field from C++. 2344 2345 2346File: gcj.info, Node: Object allocation, Next: Memory allocation, Prev: Class Initialization, Up: About CNI 2347 234812.8 Object allocation 2349====================== 2350 2351New Java objects are allocated using a "class instance creation 2352expression", e.g.: 2353 2354 new TYPE ( ... ) 2355 2356 The same syntax is used in C++. The main difference is that C++ 2357objects have to be explicitly deleted; in Java they are automatically 2358deleted by the garbage collector. Using CNI, you can allocate a new 2359Java object using standard C++ syntax and the C++ compiler will allocate 2360memory from the garbage collector. If you have overloaded 2361constructors, the compiler will choose the correct one using standard 2362C++ overload resolution rules. 2363 2364For example: 2365 2366 java::util::Hashtable *ht = new java::util::Hashtable(120); 2367 2368 2369File: gcj.info, Node: Memory allocation, Next: Arrays, Prev: Object allocation, Up: About CNI 2370 237112.9 Memory allocation 2372====================== 2373 2374When allocating memory in CNI methods it is best to handle 2375out-of-memory conditions by throwing a Java exception. These functions 2376are provided for that purpose: 2377 2378 -- Function: void* JvMalloc (jsize SIZE) 2379 Calls malloc. Throws `java.lang.OutOfMemoryError' if allocation 2380 fails. 2381 2382 -- Function: void* JvRealloc (void* PTR, jsize SIZE) 2383 Calls realloc. Throws `java.lang.OutOfMemoryError' if 2384 reallocation fails. 2385 2386 -- Function: void JvFree (void* PTR) 2387 Calls free. 2388 2389 2390File: gcj.info, Node: Arrays, Next: Methods, Prev: Memory allocation, Up: About CNI 2391 239212.10 Arrays 2393============ 2394 2395While in many ways Java is similar to C and C++, it is quite different 2396in its treatment of arrays. C arrays are based on the idea of pointer 2397arithmetic, which would be incompatible with Java's security 2398requirements. Java arrays are true objects (array types inherit from 2399`java.lang.Object'). An array-valued variable is one that contains a 2400reference (pointer) to an array object. 2401 2402 Referencing a Java array in C++ code is done using the `JArray' 2403template, which as defined as follows: 2404 2405 class __JArray : public java::lang::Object 2406 { 2407 public: 2408 int length; 2409 }; 2410 2411 template<class T> 2412 class JArray : public __JArray 2413 { 2414 T data[0]; 2415 public: 2416 T& operator[](jint i) { return data[i]; } 2417 }; 2418 2419 There are a number of `typedef's which correspond to `typedef's from 2420the JNI. Each is the type of an array holding objects of the relevant 2421type: 2422 2423 typedef __JArray *jarray; 2424 typedef JArray<jobject> *jobjectArray; 2425 typedef JArray<jboolean> *jbooleanArray; 2426 typedef JArray<jbyte> *jbyteArray; 2427 typedef JArray<jchar> *jcharArray; 2428 typedef JArray<jshort> *jshortArray; 2429 typedef JArray<jint> *jintArray; 2430 typedef JArray<jlong> *jlongArray; 2431 typedef JArray<jfloat> *jfloatArray; 2432 typedef JArray<jdouble> *jdoubleArray; 2433 2434 -- Method on template<class T>: T* elements (JArray<T> ARRAY) 2435 This template function can be used to get a pointer to the 2436 elements of the `array'. For instance, you can fetch a pointer to 2437 the integers that make up an `int[]' like so: 2438 2439 extern jintArray foo; 2440 jint *intp = elements (foo); 2441 2442 The name of this function may change in the future. 2443 2444 -- Function: jobjectArray JvNewObjectArray (jsize LENGTH, jclass 2445 KLASS, jobject INIT) 2446 This creates a new array whose elements have reference type. 2447 `klass' is the type of elements of the array and `init' is the 2448 initial value put into every slot in the array. 2449 2450 using namespace java::lang; 2451 JArray<String *> *array 2452 = (JArray<String *> *) JvNewObjectArray(length, &String::class$, NULL); 2453 245412.10.1 Creating arrays 2455----------------------- 2456 2457For each primitive type there is a function which can be used to create 2458a new array of that type. The name of the function is of the form: 2459 2460 JvNewTYPEArray 2461 2462For example: 2463 2464 JvNewBooleanArray 2465 2466can be used to create an array of Java primitive boolean types. 2467 2468The following function definition is the template for all such 2469functions: 2470 2471 -- Function: jbooleanArray JvNewBooleanArray (jint LENGTH) 2472 Create's an array LENGTH indices long. 2473 2474 -- Function: jsize JvGetArrayLength (jarray ARRAY) 2475 Returns the length of the ARRAY. 2476 2477 2478File: gcj.info, Node: Methods, Next: Strings, Prev: Arrays, Up: About CNI 2479 248012.11 Methods 2481============= 2482 2483Java methods are mapped directly into C++ methods. The header files 2484generated by `gcjh' include the appropriate method definitions. 2485Basically, the generated methods have the same names and 2486_corresponding_ types as the Java methods, and are called in the 2487natural manner. 2488 248912.11.1 Overloading 2490------------------- 2491 2492Both Java and C++ provide method overloading, where multiple methods in 2493a class have the same name, and the correct one is chosen (at compile 2494time) depending on the argument types. The rules for choosing the 2495correct method are (as expected) more complicated in C++ than in Java, 2496but given a set of overloaded methods generated by `gcjh' the C++ 2497compiler will choose the expected one. 2498 2499 Common assemblers and linkers are not aware of C++ overloading, so 2500the standard implementation strategy is to encode the parameter types 2501of a method into its assembly-level name. This encoding is called 2502"mangling", and the encoded name is the "mangled name". The same 2503mechanism is used to implement Java overloading. For C++/Java 2504interoperability, it is important that both the Java and C++ compilers 2505use the _same_ encoding scheme. 2506 250712.11.2 Static methods 2508---------------------- 2509 2510Static Java methods are invoked in CNI using the standard C++ syntax, 2511using the `::' operator rather than the `.' operator. 2512 2513For example: 2514 2515 jint i = java::lang::Math::round((jfloat) 2.3); 2516 2517C++ method definition syntax is used to define a static native method. 2518For example: 2519 2520 #include <java/lang/Integer> 2521 java::lang::Integer* 2522 java::lang::Integer::getInteger(jstring str) 2523 { 2524 ... 2525 } 2526 252712.11.3 Object Constructors 2528--------------------------- 2529 2530Constructors are called implicitly as part of object allocation using 2531the `new' operator. 2532 2533For example: 2534 2535 java::lang::Integer *x = new java::lang::Integer(234); 2536 2537 Java does not allow a constructor to be a native method. This 2538limitation can be coded round however because a constructor can _call_ 2539a native method. 2540 254112.11.4 Instance methods 2542------------------------ 2543 2544Calling a Java instance method from a C++ CNI method is done using the 2545standard C++ syntax, e.g.: 2546 2547 // First create the Java object. 2548 java::lang::Integer *x = new java::lang::Integer(234); 2549 // Now call a method. 2550 jint prim_value = x->intValue(); 2551 if (x->longValue == 0) 2552 ... 2553 2554Defining a Java native instance method is also done the natural way: 2555 2556 #include <java/lang/Integer.h> 2557 2558 jdouble 2559 java::lang:Integer::doubleValue() 2560 { 2561 return (jdouble) value; 2562 } 2563 256412.11.5 Interface methods 2565------------------------- 2566 2567In Java you can call a method using an interface reference. This is 2568supported, but not completely. *Note Interfaces::. 2569 2570 2571File: gcj.info, Node: Strings, Next: Mixing with C++, Prev: Methods, Up: About CNI 2572 257312.12 Strings 2574============= 2575 2576CNI provides a number of utility functions for working with Java Java 2577`String' objects. The names and interfaces are analogous to those of 2578JNI. 2579 2580 -- Function: jstring JvNewString (const char* CHARS, jsize LEN) 2581 Returns a Java `String' object with characters from the C string 2582 CHARS up to the index LEN in that array. 2583 2584 -- Function: jstring JvNewStringLatin1 (const char* BYTES, jsize LEN) 2585 Returns a Java `String' made up of LEN bytes from BYTES. 2586 2587 -- Function: jstring JvNewStringLatin1 (const char* BYTES) 2588 As above but the length of the `String' is `strlen(BYTES)'. 2589 2590 -- Function: jstring JvNewStringUTF (const char* BYTES) 2591 Returns a `String' which is made up of the UTF encoded characters 2592 present in the C string BYTES. 2593 2594 -- Function: jchar* JvGetStringChars (jstring STR) 2595 Returns a pointer to an array of characters making up the `String' 2596 STR. 2597 2598 -- Function: int JvGetStringUTFLength (jstring STR) 2599 Returns the number of bytes required to encode the contents of the 2600 `String' STR in UTF-8. 2601 2602 -- Function: jsize JvGetStringUTFRegion (jstring STR, jsize START, 2603 jsize LEN, char* BUF) 2604 Puts the UTF-8 encoding of a region of the `String' STR into the 2605 buffer `buf'. The region to fetch is marked by START and LEN. 2606 2607 Note that BUF is a buffer, not a C string. It is _not_ null 2608 terminated. 2609 2610 2611File: gcj.info, Node: Mixing with C++, Next: Exception Handling, Prev: Strings, Up: About CNI 2612 261312.13 Interoperating with C/C++ 2614=============================== 2615 2616Because CNI is designed to represent Java classes and methods it cannot 2617be mixed readily with C/C++ types. 2618 2619 One important restriction is that Java classes cannot have non-Java 2620type instance or static variables and cannot have methods which take 2621non-Java types as arguments or return non-Java types. 2622 2623None of the following is possible with CNI: 2624 2625 2626 class ::MyClass : public java::lang::Object 2627 { 2628 char* variable; // char* is not a valid Java type. 2629 } 2630 2631 2632 uint 2633 ::SomeClass::someMethod (char *arg) 2634 { 2635 . 2636 . 2637 . 2638 } // `uint' is not a valid Java type, neither is `char*' 2639 2640Of course, it is ok to use C/C++ types within the scope of a method: 2641 2642 jint 2643 ::SomeClass::otherMethod (jstring str) 2644 { 2645 char *arg = ... 2646 . 2647 . 2648 . 2649 } 2650 265112.13.1 RawData 2652--------------- 2653 2654The above restriction can be problematic, so CNI includes the 2655`gnu.gcj.RawData' class. The `RawData' class is a "non-scanned 2656reference" type. In other words variables declared of type `RawData' 2657can contain any data and are not checked by the compiler or memory 2658manager in any way. 2659 2660 This means that you can put C/C++ data structures (including classes) 2661in your CNI classes, as long as you use the appropriate cast. 2662 2663Here are some examples: 2664 2665 2666 class ::MyClass : public java::lang::Object 2667 { 2668 gnu.gcj.RawData string; 2669 2670 MyClass (); 2671 gnu.gcj.RawData getText (); 2672 void printText (); 2673 } 2674 2675 ::MyClass::MyClass () 2676 { 2677 char* text = ... 2678 string = text; 2679 } 2680 2681 gnu.gcj.RawData 2682 ::MyClass::getText () 2683 { 2684 return string; 2685 } 2686 2687 void 2688 ::MyClass::printText () 2689 { 2690 printf("%s\n", (char*) string); 2691 } 2692 269312.13.2 RawDataManaged 2694---------------------- 2695 2696`gnu.gcj.RawDataManaged' is another type used to indicate special data 2697used by native code. Unlike the `RawData' type, fields declared as 2698`RawDataManaged' will be "marked" by the memory manager and considered 2699for garbage collection. 2700 2701 Native data which is allocated using CNI's `JvAllocBytes()' function 2702and stored in a `RawDataManaged' will be automatically freed when the 2703Java object it is associated with becomes unreachable. 2704 270512.13.3 Native memory allocation 2706-------------------------------- 2707 2708 -- Function: void* JvAllocBytes (jsize SIZE) 2709 Allocates SIZE bytes from the heap. The memory returned is zeroed. 2710 This memory is not scanned for pointers by the garbage collector, 2711 but will be freed if no references to it are discovered. 2712 2713 This function can be useful if you need to associate some native 2714 data with a Java object. Using a CNI's special `RawDataManaged' 2715 type, native data allocated with `JvAllocBytes' will be 2716 automatically freed when the Java object itself becomes 2717 unreachable. 2718 271912.13.4 Posix signals 2720--------------------- 2721 2722On Posix based systems the `libgcj' library uses several signals 2723internally. CNI code should not attempt to use the same signals as 2724doing so may cause `libgcj' and/or the CNI code to fail. 2725 2726 SIGSEGV is used on many systems to generate `NullPointerExceptions'. 2727SIGCHLD is used internally by `Runtime.exec()'. Several other signals 2728(that vary from platform to platform) can be used by the memory manager 2729and by `Thread.interrupt()'. 2730 2731 2732File: gcj.info, Node: Exception Handling, Next: Synchronization, Prev: Mixing with C++, Up: About CNI 2733 273412.14 Exception Handling 2735======================== 2736 2737While C++ and Java share a common exception handling framework, things 2738are not yet perfectly integrated. The main issue is that the run-time 2739type information facilities of the two languages are not integrated. 2740 2741 Still, things work fairly well. You can throw a Java exception from 2742C++ using the ordinary `throw' construct, and this exception can be 2743caught by Java code. Similarly, you can catch an exception thrown from 2744Java using the C++ `catch' construct. 2745 2746Here is an example: 2747 2748 if (i >= count) 2749 throw new java::lang::IndexOutOfBoundsException(); 2750 2751 Normally, G++ will automatically detect when you are writing C++ 2752code that uses Java exceptions, and handle them appropriately. 2753However, if C++ code only needs to execute destructors when Java 2754exceptions are thrown through it, GCC will guess incorrectly. Sample 2755problematic code: 2756 2757 struct S { ~S(); }; 2758 2759 extern void bar(); // Is implemented in Java and may throw exceptions. 2760 2761 void foo() 2762 { 2763 S s; 2764 bar(); 2765 } 2766 2767 The usual effect of an incorrect guess is a link failure, 2768complaining of a missing routine called `__gxx_personality_v0'. 2769 2770 You can inform the compiler that Java exceptions are to be used in a 2771translation unit, irrespective of what it might think, by writing 2772`#pragma GCC java_exceptions' at the head of the file. This `#pragma' 2773must appear before any functions that throw or catch exceptions, or run 2774destructors when exceptions are thrown through them. 2775 2776 2777File: gcj.info, Node: Synchronization, Next: Invocation, Prev: Exception Handling, Up: About CNI 2778 277912.15 Synchronization 2780===================== 2781 2782Each Java object has an implicit monitor. The Java VM uses the 2783instruction `monitorenter' to acquire and lock a monitor, and 2784`monitorexit' to release it. 2785 2786 The corresponding CNI macros are `JvMonitorEnter' and 2787`JvMonitorExit' (JNI has similar methods `MonitorEnter' and 2788`MonitorExit'). 2789 2790 The Java source language does not provide direct access to these 2791primitives. Instead, there is a `synchronized' statement that does an 2792implicit `monitorenter' before entry to the block, and does a 2793`monitorexit' on exit from the block. Note that the lock has to be 2794released even when the block is abnormally terminated by an exception, 2795which means there is an implicit `try finally' surrounding 2796synchronization locks. 2797 2798 From C++, it makes sense to use a destructor to release a lock. CNI 2799defines the following utility class: 2800 2801 class JvSynchronize() { 2802 jobject obj; 2803 JvSynchronize(jobject o) { obj = o; JvMonitorEnter(o); } 2804 ~JvSynchronize() { JvMonitorExit(obj); } 2805 }; 2806 2807 So this Java code: 2808 2809 synchronized (OBJ) 2810 { 2811 CODE 2812 } 2813 2814might become this C++ code: 2815 2816 { 2817 JvSynchronize dummy (OBJ); 2818 CODE; 2819 } 2820 2821 Java also has methods with the `synchronized' attribute. This is 2822equivalent to wrapping the entire method body in a `synchronized' 2823statement. (Alternatively, an implementation could require the caller 2824to do the synchronization. This is not practical for a compiler, 2825because each virtual method call would have to test at run-time if 2826synchronization is needed.) Since in `gcj' the `synchronized' 2827attribute is handled by the method implementation, it is up to the 2828programmer of a synchronized native method to handle the synchronization 2829(in the C++ implementation of the method). In other words, you need to 2830manually add `JvSynchronize' in a `native synchronized' method. 2831 2832 2833File: gcj.info, Node: Invocation, Next: Reflection, Prev: Synchronization, Up: About CNI 2834 283512.16 Invocation 2836================ 2837 2838CNI permits C++ applications to make calls into Java classes, in 2839addition to allowing Java code to call into C++. Several functions, 2840known as the "invocation API", are provided to support this. 2841 2842 -- Function: jint JvCreateJavaVM (JvVMInitArgs* VM_ARGS) 2843 Initializes the Java runtime. This function performs essential 2844 initialization of the threads interface, garbage collector, 2845 exception handling and other key aspects of the runtime. It must 2846 be called once by an application with a non-Java `main()' 2847 function, before any other Java or CNI calls are made. It is 2848 safe, but not recommended, to call `JvCreateJavaVM()' more than 2849 once provided it is only called from a single thread. The VMARGS 2850 parameter can be used to specify initialization parameters for the 2851 Java runtime. It may be `NULL'. 2852 2853 JvVMInitArgs represents a list of virtual machine initialization 2854 arguments. `JvCreateJavaVM()' ignores the version field. 2855 2856 typedef struct JvVMOption 2857 { 2858 // a VM initialization option 2859 char* optionString; 2860 // extra information associated with this option 2861 void* extraInfo; 2862 } JvVMOption; 2863 2864 typedef struct JvVMInitArgs 2865 { 2866 // for compatibility with JavaVMInitArgs 2867 jint version; 2868 2869 // number of VM initialization options 2870 jint nOptions; 2871 2872 // an array of VM initialization options 2873 JvVMOption* options; 2874 2875 // true if the option parser should ignore unrecognized options 2876 jboolean ignoreUnrecognized; 2877 } JvVMInitArgs; 2878 2879 `JvCreateJavaVM()' returns `0' upon success, or `-1' if the 2880 runtime is already initialized. 2881 2882 _Note:_ In GCJ 3.1, the `vm_args' parameter is ignored. It is 2883 recognized and used as of release 4.0. 2884 2885 -- Function: java::lang::Thread* JvAttachCurrentThread (jstring NAME, 2886 java::lang::ThreadGroup* GROUP) 2887 Registers an existing thread with the Java runtime. This must be 2888 called once from each thread, before that thread makes any other 2889 Java or CNI calls. It must be called after `JvCreateJavaVM'. NAME 2890 specifies a name for the thread. It may be `NULL', in which case a 2891 name will be generated. GROUP is the ThreadGroup in which this 2892 thread will be a member. If it is `NULL', the thread will be a 2893 member of the main thread group. The return value is the Java 2894 `Thread' object that represents the thread. It is safe to call 2895 `JvAttachCurrentThread()' more than once from the same thread. If 2896 the thread is already attached, the call is ignored and the current 2897 thread object is returned. 2898 2899 -- Function: jint JvDetachCurrentThread () 2900 Unregisters a thread from the Java runtime. This should be called 2901 by threads that were attached using `JvAttachCurrentThread()', 2902 after they have finished making calls to Java code. This ensures 2903 that any resources associated with the thread become eligible for 2904 garbage collection. This function returns `0' upon success, or 2905 `-1' if the current thread is not attached. 2906 290712.16.1 Handling uncaught exceptions 2908------------------------------------ 2909 2910If an exception is thrown from Java code called using the invocation 2911API, and no handler for the exception can be found, the runtime will 2912abort the application. In order to make the application more robust, it 2913is recommended that code which uses the invocation API be wrapped by a 2914top-level try/catch block that catches all Java exceptions. 2915 291612.16.2 Example 2917--------------- 2918 2919The following code demonstrates the use of the invocation API. In this 2920example, the C++ application initializes the Java runtime and attaches 2921itself. The `java.lang.System' class is initialized in order to access 2922its `out' field, and a Java string is printed. Finally, the thread is 2923detached from the runtime once it has finished making Java calls. 2924Everything is wrapped with a try/catch block to provide a default 2925handler for any uncaught exceptions. 2926 2927 The example can be compiled with `c++ -c test.cc; gcj test.o'. 2928 2929 // test.cc 2930 #include <gcj/cni.h> 2931 #include <java/lang/System.h> 2932 #include <java/io/PrintStream.h> 2933 #include <java/lang/Throwable.h> 2934 2935 int main(int argc, char *argv[]) 2936 { 2937 using namespace java::lang; 2938 2939 try 2940 { 2941 JvCreateJavaVM(NULL); 2942 JvAttachCurrentThread(NULL, NULL); 2943 2944 String *message = JvNewStringLatin1("Hello from C++"); 2945 JvInitClass(&System::class$); 2946 System::out->println(message); 2947 2948 JvDetachCurrentThread(); 2949 } 2950 catch (Throwable *t) 2951 { 2952 System::err->println(JvNewStringLatin1("Unhandled Java exception:")); 2953 t->printStackTrace(); 2954 } 2955 } 2956 2957 2958File: gcj.info, Node: Reflection, Prev: Invocation, Up: About CNI 2959 296012.17 Reflection 2961================ 2962 2963Reflection is possible with CNI code, it functions similarly to how it 2964functions with JNI. 2965 2966 The types `jfieldID' and `jmethodID' are as in JNI. 2967 2968The functions: 2969 2970 * `JvFromReflectedField', 2971 2972 * `JvFromReflectedMethod', 2973 2974 * `JvToReflectedField' 2975 2976 * `JvToFromReflectedMethod' 2977 2978will be added shortly, as will other functions corresponding to JNI. 2979 2980 2981File: gcj.info, Node: System properties, Next: Resources, Prev: About CNI, Up: Top 2982 298313 System properties 2984******************** 2985 2986The runtime behavior of the `libgcj' library can be modified by setting 2987certain system properties. These properties can be compiled into the 2988program using the `-DNAME[=VALUE]' option to `gcj' or by setting them 2989explicitly in the program by calling the 2990`java.lang.System.setProperty()' method. Some system properties are 2991only used for informational purposes (like giving a version number or a 2992user name). A program can inspect the current value of a property by 2993calling the `java.lang.System.getProperty()' method. 2994 2995* Menu: 2996 2997* Standard Properties:: Standard properties supported by `libgcj' 2998* GNU Classpath Properties:: Properties found in Classpath based libraries 2999* libgcj Runtime Properties:: Properties specific to `libgcj' 3000 3001 3002File: gcj.info, Node: Standard Properties, Next: GNU Classpath Properties, Up: System properties 3003 300413.1 Standard Properties 3005======================== 3006 3007The following properties are normally found in all implementations of 3008the core libraries for the Java language. 3009 3010`java.version' 3011 The `libgcj' version number. 3012 3013`java.vendor' 3014 Set to `The Free Software Foundation, Inc.' 3015 3016`java.vendor.url' 3017 Set to `http://gcc.gnu.org/java/'. 3018 3019`java.home' 3020 The directory where `gcj' was installed. Taken from the `--prefix' 3021 option given to `configure'. 3022 3023`java.class.version' 3024 The class format version number supported by the libgcj byte code 3025 interpreter. (Currently `46.0') 3026 3027`java.vm.specification.version' 3028 The Virtual Machine Specification version implemented by `libgcj'. 3029 (Currently `1.0') 3030 3031`java.vm.specification.vendor' 3032 The name of the Virtual Machine specification designer. 3033 3034`java.vm.specification.name' 3035 The name of the Virtual Machine specification (Set to `Java 3036 Virtual Machine Specification'). 3037 3038`java.vm.version' 3039 The `gcj' version number. 3040 3041`java.vm.vendor' 3042 Set to `The Free Software Foundation, Inc.' 3043 3044`java.vm.name' 3045 Set to `GNU libgcj'. 3046 3047`java.specification.version' 3048 The Runtime Environment specification version implemented by 3049 `libgcj'. (Currently set to `1.3') 3050 3051`java.specification.vendor' 3052 The Runtime Environment specification designer. 3053 3054`java.specification.name' 3055 The name of the Runtime Environment specification (Set to `Java 3056 Platform API Specification'). 3057 3058`java.class.path' 3059 The paths (jar files, zip files and directories) used for finding 3060 class files. 3061 3062`java.library.path' 3063 Directory path used for finding native libraries. 3064 3065`java.io.tmpdir' 3066 The directory used to put temporary files in. 3067 3068`java.compiler' 3069 Name of the Just In Time compiler to use by the byte code 3070 interpreter. Currently not used in `libgcj'. 3071 3072`java.ext.dirs' 3073 Directories containing jar files with extra libraries. Will be 3074 used when resolving classes. 3075 3076`java.protocol.handler.pkgs' 3077 A `|' separated list of package names that is used to find classes 3078 that implement handlers for `java.net.URL'. 3079 3080`java.rmi.server.codebase' 3081 A list of URLs that is used by the `java.rmi.server.RMIClassLoader' 3082 to load classes from. 3083 3084`jdbc.drivers' 3085 A list of class names that will be loaded by the 3086 `java.sql.DriverManager' when it starts up. 3087 3088`file.separator' 3089 The separator used in when directories are included in a filename 3090 (normally `/' or `\' ). 3091 3092`file.encoding' 3093 The default character encoding used when converting platform 3094 native files to Unicode (usually set to `8859_1'). 3095 3096`path.separator' 3097 The standard separator used when a string contains multiple paths 3098 (normally `:' or `;'), the string is usually not a valid character 3099 to use in normal directory names.) 3100 3101`line.separator' 3102 The default line separator used on the platform (normally `\n', 3103 `\r' or a combination of those two characters). 3104 3105`policy.provider' 3106 The class name used for the default policy provider returned by 3107 `java.security.Policy.getPolicy'. 3108 3109`user.name' 3110 The name of the user running the program. Can be the full name, 3111 the login name or empty if unknown. 3112 3113`user.home' 3114 The default directory to put user specific files in. 3115 3116`user.dir' 3117 The current working directory from which the program was started. 3118 3119`user.language' 3120 The default language as used by the `java.util.Locale' class. 3121 3122`user.region' 3123 The default region as used by the `java.util.Local' class. 3124 3125`user.variant' 3126 The default variant of the language and region local used. 3127 3128`user.timezone' 3129 The default timezone as used by the `java.util.TimeZone' class. 3130 3131`os.name' 3132 The operating system/kernel name that the program runs on. 3133 3134`os.arch' 3135 The hardware that we are running on. 3136 3137`os.version' 3138 The version number of the operating system/kernel. 3139 3140`awt.appletWarning' 3141 The string to display when an untrusted applet is displayed. 3142 Returned by `java.awt.Window.getWarningString()' when the window is 3143 "insecure". 3144 3145`awt.toolkit' 3146 The class name used for initializing the default 3147 `java.awt.Toolkit'. Defaults to `gnu.awt.gtk.GtkToolkit'. 3148 3149`http.proxyHost' 3150 Name of proxy host for http connections. 3151 3152`http.proxyPort' 3153 Port number to use when a proxy host is in use. 3154 3155 3156 3157File: gcj.info, Node: GNU Classpath Properties, Next: libgcj Runtime Properties, Prev: Standard Properties, Up: System properties 3158 315913.2 GNU Classpath Properties 3160============================= 3161 3162`libgcj' is based on the GNU Classpath (Essential Libraries for Java) a 3163GNU project to create free core class libraries for use with virtual 3164machines and compilers for the Java language. The following properties 3165are common to libraries based on GNU Classpath. 3166 3167`gcj.dumpobject' 3168 Enables printing serialization debugging by the 3169 `java.io.ObjectInput' and `java.io.ObjectOutput' classes when set 3170 to something else then the empty string. Only used when running a 3171 debug build of the library. 3172 3173`gnu.classpath.vm.shortname' 3174 This is a succinct name of the virtual machine. For `libgcj', 3175 this will always be `libgcj'. 3176 3177`gnu.classpath.home.url' 3178 A base URL used for finding system property files (e.g., 3179 `classpath.security'). By default this is a `file:' URL pointing 3180 to the `lib' directory under `java.home'. 3181 3182 3183 3184File: gcj.info, Node: libgcj Runtime Properties, Prev: GNU Classpath Properties, Up: System properties 3185 318613.3 libgcj Runtime Properties 3187============================== 3188 3189The following properties are specific to the `libgcj' runtime and will 3190normally not be found in other core libraries for the java language. 3191 3192`java.fullversion' 3193 The combination of `java.vm.name' and `java.vm.version'. 3194 3195`java.vm.info' 3196 Same as `java.fullversion'. 3197 3198`impl.prefix' 3199 Used by the `java.net.DatagramSocket' class when set to something 3200 else then the empty string. When set all newly created 3201 `DatagramSocket's will try to load a class 3202 `java.net.[impl.prefix]DatagramSocketImpl' instead of the normal 3203 `java.net.PlainDatagramSocketImpl'. 3204 3205`gnu.gcj.progname' 3206 The class or binary name that was used to invoke the program. This 3207 will be the name of the "main" class in the case where the `gij' 3208 front end is used, or the program binary name in the case where an 3209 application is compiled to a native binary. 3210 3211`gnu.gcj.user.realname' 3212 The real name of the user, as taken from the password file. This 3213 may not always hold only the user's name (as some sites put extra 3214 information in this field). Also, this property is not available 3215 on all platforms. 3216 3217`gnu.gcj.runtime.NameFinder.use_addr2line' 3218 Whether an external process, `addr2line', should be used to 3219 determine line number information when tracing the stack. Setting 3220 this to `false' may suppress line numbers when printing stack 3221 traces and when using the java.util.logging infrastructure. 3222 However, performance may improve significantly for applications 3223 that print stack traces or make logging calls frequently. 3224 3225`gnu.gcj.runtime.NameFinder.show_raw' 3226 Whether the address of a stack frame should be printed when the 3227 line number is unavailable. Setting this to `true' will cause the 3228 name of the object and the offset within that object to be printed 3229 when no line number is available. This allows for off-line 3230 decoding of stack traces if necessary debug information is 3231 available. The default is `false', no raw addresses are printed. 3232 3233`gnu.gcj.runtime.NameFinder.remove_unknown' 3234 Whether stack frames for non-java code should be included in a 3235 stack trace. The default value is `true', stack frames for 3236 non-java code are suppressed. Setting this to `false' will cause 3237 any non-java stack frames to be printed in addition to frames for 3238 the java code. 3239 3240`gnu.gcj.runtime.VMClassLoader.library_control' 3241 This controls how shared libraries are automatically loaded by the 3242 built-in class loader. If this property is set to `full', a full 3243 search is done for each requested class. If this property is set 3244 to `cache', then any failed lookups are cached and not tried again. 3245 If this property is set to `never' (the default), then lookups are 3246 never done. For more information, *Note Extensions::. 3247 3248`gnu.gcj.runtime.endorsed.dirs' 3249 This is like the standard `java.endorsed.dirs', property, but 3250 specifies some extra directories which are searched after the 3251 standard endorsed directories. This is primarily useful for 3252 telling `libgcj' about additional libraries which are ordinarily 3253 incorporated into the JDK, and which should be loaded by the 3254 bootstrap class loader, but which are not yet part of `libgcj' 3255 itself for some reason. 3256 3257`gnu.gcj.jit.compiler' 3258 This is the full path to `gcj' executable which should be used to 3259 compile classes just-in-time when `ClassLoader.defineClass' is 3260 called. If not set, `gcj' will not be invoked by the runtime; 3261 this can also be controlled via `Compiler.disable'. 3262 3263`gnu.gcj.jit.options' 3264 This is a space-separated string of options which should be passed 3265 to `gcj' when in JIT mode. If not set, a sensible default is 3266 chosen. 3267 3268`gnu.gcj.jit.cachedir' 3269 This is the directory where cached shared library files are 3270 stored. If not set, JIT compilation is disabled. This should 3271 never be set to a directory that is writable by any other user. 3272 3273`gnu.gcj.precompiled.db.path' 3274 This is a sequence of file names, each referring to a file created 3275 by `gcj-dbtool'. These files will be used by `libgcj' to find 3276 shared libraries corresponding to classes that are loaded from 3277 bytecode. `libgcj' often has a built-in default database; it can 3278 be queried using `gcj-dbtool -p'. 3279 3280 3281 3282File: gcj.info, Node: Resources, Next: Index, Prev: System properties, Up: Top 3283 328414 Resources 3285************ 3286 3287While writing `gcj' and `libgcj' we have, of course, relied heavily on 3288documentation from Sun Microsystems. In particular we have used The 3289Java Language Specification (both first and second editions), the Java 3290Class Libraries (volumes one and two), and the Java Virtual Machine 3291Specification. In addition we've used the online documentation at 3292`http://java.sun.com/'. 3293 3294 The current `gcj' home page is `http://gcc.gnu.org/java/'. 3295 3296 For more information on gcc, see `http://gcc.gnu.org/'. 3297 3298 Some `libgcj' testing is done using the Mauve test suite. This is a 3299free software Java class library test suite which is being written 3300because the JCK is not free. See `http://sources.redhat.com/mauve/' 3301for more information. 3302 3303 3304File: gcj.info, Node: Index, Prev: Resources, Up: Top 3305 3306Index 3307***** 3308 3309�[index�] 3310* Menu: 3311 3312* class path: Input Options. (line 6) 3313* class$: Reference types. (line 20) 3314* elements on template<class T>: Arrays. (line 46) 3315* FDL, GNU Free Documentation License: GNU Free Documentation License. 3316 (line 6) 3317* GCJ_PROPERTIES: Extensions. (line 56) 3318* jclass: Reference types. (line 16) 3319* jobject: Reference types. (line 16) 3320* jstring: Reference types. (line 16) 3321* JvAllocBytes: Mixing with C++. (line 99) 3322* JvAttachCurrentThread: Invocation. (line 55) 3323* JvCreateJavaVM: Invocation. (line 11) 3324* JvDetachCurrentThread: Invocation. (line 68) 3325* JvFree: Memory allocation. (line 19) 3326* JvGetArrayLength: Arrays. (line 86) 3327* JvGetStringChars: Strings. (line 25) 3328* JvGetStringUTFLength: Strings. (line 29) 3329* JvGetStringUTFRegion: Strings. (line 34) 3330* JvMalloc: Memory allocation. (line 11) 3331* JvNewBooleanArray: Arrays. (line 83) 3332* JvNewObjectArray: Arrays. (line 57) 3333* JvNewString: Strings. (line 11) 3334* JvNewStringLatin1: Strings. (line 15) 3335* JvNewStringUTF: Strings. (line 21) 3336* JvPrimClass: Primitive types. (line 36) 3337* JvRealloc: Memory allocation. (line 15) 3338 3339 3340 3341Tag Table: 3342Node: Top2846 3343Node: Copying4168 3344Node: GNU Free Documentation License23363 3345Node: Invoking gcj45775 3346Node: Input and output files46474 3347Node: Input Options48000 3348Node: Encodings51148 3349Node: Warnings52354 3350Node: Linking53467 3351Node: Code Generation56406 3352Node: Configure-time Options62956 3353Node: Compatibility64379 3354Node: Limitations64859 3355Node: Extensions66441 3356Node: Invoking gcjh69535 3357Node: Invoking gjnih71890 3358Node: Invoking jv-scan74078 3359Node: Invoking jcf-dump75120 3360Node: Invoking gij76068 3361Node: Invoking gcj-dbtool79319 3362Node: Invoking jv-convert81785 3363Node: Invoking grmic82864 3364Node: Invoking grmiregistry84254 3365Node: About CNI84667 3366Node: Basic concepts86109 3367Node: Packages89005 3368Node: Primitive types91333 3369Node: Reference types93011 3370Node: Interfaces94100 3371Node: Objects and Classes95011 3372Node: Class Initialization97206 3373Node: Object allocation99548 3374Node: Memory allocation100338 3375Node: Arrays100970 3376Node: Methods103781 3377Node: Strings106602 3378Node: Mixing with C++108086 3379Node: Exception Handling111557 3380Node: Synchronization113191 3381Node: Invocation115181 3382Node: Reflection120117 3383Node: System properties120578 3384Node: Standard Properties121455 3385Node: GNU Classpath Properties125887 3386Node: libgcj Runtime Properties126934 3387Node: Resources131436 3388Node: Index132274 3389 3390End Tag Table 3391