1 /* 2 * Copyright (c) 1994, 2020, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.lang; 27 28 import java.lang.invoke.MethodHandles; 29 import java.lang.constant.Constable; 30 import java.lang.constant.ConstantDesc; 31 import java.util.Optional; 32 33 import jdk.internal.math.FloatingDecimal; 34 import jdk.internal.vm.annotation.IntrinsicCandidate; 35 36 /** 37 * The {@code Float} class wraps a value of primitive type 38 * {@code float} in an object. An object of type 39 * {@code Float} contains a single field whose type is 40 * {@code float}. 41 * 42 * <p>In addition, this class provides several methods for converting a 43 * {@code float} to a {@code String} and a 44 * {@code String} to a {@code float}, as well as other 45 * constants and methods useful when dealing with a 46 * {@code float}. 47 * 48 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a> 49 * class; programmers should treat instances that are 50 * {@linkplain #equals(Object) equal} as interchangeable and should not 51 * use instances for synchronization, or unpredictable behavior may 52 * occur. For example, in a future release, synchronization may fail. 53 * 54 * @author Lee Boynton 55 * @author Arthur van Hoff 56 * @author Joseph D. Darcy 57 * @since 1.0 58 */ 59 @jdk.internal.ValueBased 60 public final class Float extends Number 61 implements Comparable<Float>, Constable, ConstantDesc { 62 /** 63 * A constant holding the positive infinity of type 64 * {@code float}. It is equal to the value returned by 65 * {@code Float.intBitsToFloat(0x7f800000)}. 66 */ 67 public static final float POSITIVE_INFINITY = 1.0f / 0.0f; 68 69 /** 70 * A constant holding the negative infinity of type 71 * {@code float}. It is equal to the value returned by 72 * {@code Float.intBitsToFloat(0xff800000)}. 73 */ 74 public static final float NEGATIVE_INFINITY = -1.0f / 0.0f; 75 76 /** 77 * A constant holding a Not-a-Number (NaN) value of type 78 * {@code float}. It is equivalent to the value returned by 79 * {@code Float.intBitsToFloat(0x7fc00000)}. 80 */ 81 public static final float NaN = 0.0f / 0.0f; 82 83 /** 84 * A constant holding the largest positive finite value of type 85 * {@code float}, (2-2<sup>-23</sup>)·2<sup>127</sup>. 86 * It is equal to the hexadecimal floating-point literal 87 * {@code 0x1.fffffeP+127f} and also equal to 88 * {@code Float.intBitsToFloat(0x7f7fffff)}. 89 */ 90 public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f 91 92 /** 93 * A constant holding the smallest positive normal value of type 94 * {@code float}, 2<sup>-126</sup>. It is equal to the 95 * hexadecimal floating-point literal {@code 0x1.0p-126f} and also 96 * equal to {@code Float.intBitsToFloat(0x00800000)}. 97 * 98 * @since 1.6 99 */ 100 public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f 101 102 /** 103 * A constant holding the smallest positive nonzero value of type 104 * {@code float}, 2<sup>-149</sup>. It is equal to the 105 * hexadecimal floating-point literal {@code 0x0.000002P-126f} 106 * and also equal to {@code Float.intBitsToFloat(0x1)}. 107 */ 108 public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f 109 110 /** 111 * Maximum exponent a finite {@code float} variable may have. It 112 * is equal to the value returned by {@code 113 * Math.getExponent(Float.MAX_VALUE)}. 114 * 115 * @since 1.6 116 */ 117 public static final int MAX_EXPONENT = 127; 118 119 /** 120 * Minimum exponent a normalized {@code float} variable may have. 121 * It is equal to the value returned by {@code 122 * Math.getExponent(Float.MIN_NORMAL)}. 123 * 124 * @since 1.6 125 */ 126 public static final int MIN_EXPONENT = -126; 127 128 /** 129 * The number of bits used to represent a {@code float} value. 130 * 131 * @since 1.5 132 */ 133 public static final int SIZE = 32; 134 135 /** 136 * The number of bytes used to represent a {@code float} value. 137 * 138 * @since 1.8 139 */ 140 public static final int BYTES = SIZE / Byte.SIZE; 141 142 /** 143 * The {@code Class} instance representing the primitive type 144 * {@code float}. 145 * 146 * @since 1.1 147 */ 148 @SuppressWarnings("unchecked") 149 public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float"); 150 151 /** 152 * Returns a string representation of the {@code float} 153 * argument. All characters mentioned below are ASCII characters. 154 * <ul> 155 * <li>If the argument is NaN, the result is the string 156 * "{@code NaN}". 157 * <li>Otherwise, the result is a string that represents the sign and 158 * magnitude (absolute value) of the argument. If the sign is 159 * negative, the first character of the result is 160 * '{@code -}' ({@code '\u005Cu002D'}); if the sign is 161 * positive, no sign character appears in the result. As for 162 * the magnitude <i>m</i>: 163 * <ul> 164 * <li>If <i>m</i> is infinity, it is represented by the characters 165 * {@code "Infinity"}; thus, positive infinity produces 166 * the result {@code "Infinity"} and negative infinity 167 * produces the result {@code "-Infinity"}. 168 * <li>If <i>m</i> is zero, it is represented by the characters 169 * {@code "0.0"}; thus, negative zero produces the result 170 * {@code "-0.0"} and positive zero produces the result 171 * {@code "0.0"}. 172 * <li> If <i>m</i> is greater than or equal to 10<sup>-3</sup> but 173 * less than 10<sup>7</sup>, then it is represented as the 174 * integer part of <i>m</i>, in decimal form with no leading 175 * zeroes, followed by '{@code .}' 176 * ({@code '\u005Cu002E'}), followed by one or more 177 * decimal digits representing the fractional part of 178 * <i>m</i>. 179 * <li> If <i>m</i> is less than 10<sup>-3</sup> or greater than or 180 * equal to 10<sup>7</sup>, then it is represented in 181 * so-called "computerized scientific notation." Let <i>n</i> 182 * be the unique integer such that 10<sup><i>n</i> </sup>≤ 183 * <i>m</i> {@literal <} 10<sup><i>n</i>+1</sup>; then let <i>a</i> 184 * be the mathematically exact quotient of <i>m</i> and 185 * 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. 186 * The magnitude is then represented as the integer part of 187 * <i>a</i>, as a single decimal digit, followed by 188 * '{@code .}' ({@code '\u005Cu002E'}), followed by 189 * decimal digits representing the fractional part of 190 * <i>a</i>, followed by the letter '{@code E}' 191 * ({@code '\u005Cu0045'}), followed by a representation 192 * of <i>n</i> as a decimal integer, as produced by the 193 * method {@link java.lang.Integer#toString(int)}. 194 * 195 * </ul> 196 * </ul> 197 * How many digits must be printed for the fractional part of 198 * <i>m</i> or <i>a</i>? There must be at least one digit 199 * to represent the fractional part, and beyond that as many, but 200 * only as many, more digits as are needed to uniquely distinguish 201 * the argument value from adjacent values of type 202 * {@code float}. That is, suppose that <i>x</i> is the 203 * exact mathematical value represented by the decimal 204 * representation produced by this method for a finite nonzero 205 * argument <i>f</i>. Then <i>f</i> must be the {@code float} 206 * value nearest to <i>x</i>; or, if two {@code float} values are 207 * equally close to <i>x</i>, then <i>f</i> must be one of 208 * them and the least significant bit of the significand of 209 * <i>f</i> must be {@code 0}. 210 * 211 * <p>To create localized string representations of a floating-point 212 * value, use subclasses of {@link java.text.NumberFormat}. 213 * 214 * @param f the float to be converted. 215 * @return a string representation of the argument. 216 */ toString(float f)217 public static String toString(float f) { 218 return FloatingDecimal.toJavaFormatString(f); 219 } 220 221 /** 222 * Returns a hexadecimal string representation of the 223 * {@code float} argument. All characters mentioned below are 224 * ASCII characters. 225 * 226 * <ul> 227 * <li>If the argument is NaN, the result is the string 228 * "{@code NaN}". 229 * <li>Otherwise, the result is a string that represents the sign and 230 * magnitude (absolute value) of the argument. If the sign is negative, 231 * the first character of the result is '{@code -}' 232 * ({@code '\u005Cu002D'}); if the sign is positive, no sign character 233 * appears in the result. As for the magnitude <i>m</i>: 234 * 235 * <ul> 236 * <li>If <i>m</i> is infinity, it is represented by the string 237 * {@code "Infinity"}; thus, positive infinity produces the 238 * result {@code "Infinity"} and negative infinity produces 239 * the result {@code "-Infinity"}. 240 * 241 * <li>If <i>m</i> is zero, it is represented by the string 242 * {@code "0x0.0p0"}; thus, negative zero produces the result 243 * {@code "-0x0.0p0"} and positive zero produces the result 244 * {@code "0x0.0p0"}. 245 * 246 * <li>If <i>m</i> is a {@code float} value with a 247 * normalized representation, substrings are used to represent the 248 * significand and exponent fields. The significand is 249 * represented by the characters {@code "0x1."} 250 * followed by a lowercase hexadecimal representation of the rest 251 * of the significand as a fraction. Trailing zeros in the 252 * hexadecimal representation are removed unless all the digits 253 * are zero, in which case a single zero is used. Next, the 254 * exponent is represented by {@code "p"} followed 255 * by a decimal string of the unbiased exponent as if produced by 256 * a call to {@link Integer#toString(int) Integer.toString} on the 257 * exponent value. 258 * 259 * <li>If <i>m</i> is a {@code float} value with a subnormal 260 * representation, the significand is represented by the 261 * characters {@code "0x0."} followed by a 262 * hexadecimal representation of the rest of the significand as a 263 * fraction. Trailing zeros in the hexadecimal representation are 264 * removed. Next, the exponent is represented by 265 * {@code "p-126"}. Note that there must be at 266 * least one nonzero digit in a subnormal significand. 267 * 268 * </ul> 269 * 270 * </ul> 271 * 272 * <table class="striped"> 273 * <caption>Examples</caption> 274 * <thead> 275 * <tr><th scope="col">Floating-point Value</th><th scope="col">Hexadecimal String</th> 276 * </thead> 277 * <tbody> 278 * <tr><th scope="row">{@code 1.0}</th> <td>{@code 0x1.0p0}</td> 279 * <tr><th scope="row">{@code -1.0}</th> <td>{@code -0x1.0p0}</td> 280 * <tr><th scope="row">{@code 2.0}</th> <td>{@code 0x1.0p1}</td> 281 * <tr><th scope="row">{@code 3.0}</th> <td>{@code 0x1.8p1}</td> 282 * <tr><th scope="row">{@code 0.5}</th> <td>{@code 0x1.0p-1}</td> 283 * <tr><th scope="row">{@code 0.25}</th> <td>{@code 0x1.0p-2}</td> 284 * <tr><th scope="row">{@code Float.MAX_VALUE}</th> 285 * <td>{@code 0x1.fffffep127}</td> 286 * <tr><th scope="row">{@code Minimum Normal Value}</th> 287 * <td>{@code 0x1.0p-126}</td> 288 * <tr><th scope="row">{@code Maximum Subnormal Value}</th> 289 * <td>{@code 0x0.fffffep-126}</td> 290 * <tr><th scope="row">{@code Float.MIN_VALUE}</th> 291 * <td>{@code 0x0.000002p-126}</td> 292 * </tbody> 293 * </table> 294 * @param f the {@code float} to be converted. 295 * @return a hex string representation of the argument. 296 * @since 1.5 297 * @author Joseph D. Darcy 298 */ toHexString(float f)299 public static String toHexString(float f) { 300 if (Math.abs(f) < Float.MIN_NORMAL 301 && f != 0.0f ) {// float subnormal 302 // Adjust exponent to create subnormal double, then 303 // replace subnormal double exponent with subnormal float 304 // exponent 305 String s = Double.toHexString(Math.scalb((double)f, 306 /* -1022+126 */ 307 Double.MIN_EXPONENT- 308 Float.MIN_EXPONENT)); 309 return s.replaceFirst("p-1022$", "p-126"); 310 } 311 else // double string will be the same as float string 312 return Double.toHexString(f); 313 } 314 315 /** 316 * Returns a {@code Float} object holding the 317 * {@code float} value represented by the argument string 318 * {@code s}. 319 * 320 * <p>If {@code s} is {@code null}, then a 321 * {@code NullPointerException} is thrown. 322 * 323 * <p>Leading and trailing whitespace characters in {@code s} 324 * are ignored. Whitespace is removed as if by the {@link 325 * String#trim} method; that is, both ASCII space and control 326 * characters are removed. The rest of {@code s} should 327 * constitute a <i>FloatValue</i> as described by the lexical 328 * syntax rules: 329 * 330 * <blockquote> 331 * <dl> 332 * <dt><i>FloatValue:</i> 333 * <dd><i>Sign<sub>opt</sub></i> {@code NaN} 334 * <dd><i>Sign<sub>opt</sub></i> {@code Infinity} 335 * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i> 336 * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i> 337 * <dd><i>SignedInteger</i> 338 * </dl> 339 * 340 * <dl> 341 * <dt><i>HexFloatingPointLiteral</i>: 342 * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i> 343 * </dl> 344 * 345 * <dl> 346 * <dt><i>HexSignificand:</i> 347 * <dd><i>HexNumeral</i> 348 * <dd><i>HexNumeral</i> {@code .} 349 * <dd>{@code 0x} <i>HexDigits<sub>opt</sub> 350 * </i>{@code .}<i> HexDigits</i> 351 * <dd>{@code 0X}<i> HexDigits<sub>opt</sub> 352 * </i>{@code .} <i>HexDigits</i> 353 * </dl> 354 * 355 * <dl> 356 * <dt><i>BinaryExponent:</i> 357 * <dd><i>BinaryExponentIndicator SignedInteger</i> 358 * </dl> 359 * 360 * <dl> 361 * <dt><i>BinaryExponentIndicator:</i> 362 * <dd>{@code p} 363 * <dd>{@code P} 364 * </dl> 365 * 366 * </blockquote> 367 * 368 * where <i>Sign</i>, <i>FloatingPointLiteral</i>, 369 * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and 370 * <i>FloatTypeSuffix</i> are as defined in the lexical structure 371 * sections of 372 * <cite>The Java Language Specification</cite>, 373 * except that underscores are not accepted between digits. 374 * If {@code s} does not have the form of 375 * a <i>FloatValue</i>, then a {@code NumberFormatException} 376 * is thrown. Otherwise, {@code s} is regarded as 377 * representing an exact decimal value in the usual 378 * "computerized scientific notation" or as an exact 379 * hexadecimal value; this exact numerical value is then 380 * conceptually converted to an "infinitely precise" 381 * binary value that is then rounded to type {@code float} 382 * by the usual round-to-nearest rule of IEEE 754 floating-point 383 * arithmetic, which includes preserving the sign of a zero 384 * value. 385 * 386 * Note that the round-to-nearest rule also implies overflow and 387 * underflow behaviour; if the exact value of {@code s} is large 388 * enough in magnitude (greater than or equal to ({@link 389 * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2), 390 * rounding to {@code float} will result in an infinity and if the 391 * exact value of {@code s} is small enough in magnitude (less 392 * than or equal to {@link #MIN_VALUE}/2), rounding to float will 393 * result in a zero. 394 * 395 * Finally, after rounding a {@code Float} object representing 396 * this {@code float} value is returned. 397 * 398 * <p>To interpret localized string representations of a 399 * floating-point value, use subclasses of {@link 400 * java.text.NumberFormat}. 401 * 402 * <p>Note that trailing format specifiers, specifiers that 403 * determine the type of a floating-point literal 404 * ({@code 1.0f} is a {@code float} value; 405 * {@code 1.0d} is a {@code double} value), do 406 * <em>not</em> influence the results of this method. In other 407 * words, the numerical value of the input string is converted 408 * directly to the target floating-point type. In general, the 409 * two-step sequence of conversions, string to {@code double} 410 * followed by {@code double} to {@code float}, is 411 * <em>not</em> equivalent to converting a string directly to 412 * {@code float}. For example, if first converted to an 413 * intermediate {@code double} and then to 414 * {@code float}, the string<br> 415 * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br> 416 * results in the {@code float} value 417 * {@code 1.0000002f}; if the string is converted directly to 418 * {@code float}, <code>1.000000<b>1</b>f</code> results. 419 * 420 * <p>To avoid calling this method on an invalid string and having 421 * a {@code NumberFormatException} be thrown, the documentation 422 * for {@link Double#valueOf Double.valueOf} lists a regular 423 * expression which can be used to screen the input. 424 * 425 * @param s the string to be parsed. 426 * @return a {@code Float} object holding the value 427 * represented by the {@code String} argument. 428 * @throws NumberFormatException if the string does not contain a 429 * parsable number. 430 */ valueOf(String s)431 public static Float valueOf(String s) throws NumberFormatException { 432 return new Float(parseFloat(s)); 433 } 434 435 /** 436 * Returns a {@code Float} instance representing the specified 437 * {@code float} value. 438 * If a new {@code Float} instance is not required, this method 439 * should generally be used in preference to the constructor 440 * {@link #Float(float)}, as this method is likely to yield 441 * significantly better space and time performance by caching 442 * frequently requested values. 443 * 444 * @param f a float value. 445 * @return a {@code Float} instance representing {@code f}. 446 * @since 1.5 447 */ 448 @IntrinsicCandidate valueOf(float f)449 public static Float valueOf(float f) { 450 return new Float(f); 451 } 452 453 /** 454 * Returns a new {@code float} initialized to the value 455 * represented by the specified {@code String}, as performed 456 * by the {@code valueOf} method of class {@code Float}. 457 * 458 * @param s the string to be parsed. 459 * @return the {@code float} value represented by the string 460 * argument. 461 * @throws NullPointerException if the string is null 462 * @throws NumberFormatException if the string does not contain a 463 * parsable {@code float}. 464 * @see java.lang.Float#valueOf(String) 465 * @since 1.2 466 */ parseFloat(String s)467 public static float parseFloat(String s) throws NumberFormatException { 468 return FloatingDecimal.parseFloat(s); 469 } 470 471 /** 472 * Returns {@code true} if the specified number is a 473 * Not-a-Number (NaN) value, {@code false} otherwise. 474 * 475 * @param v the value to be tested. 476 * @return {@code true} if the argument is NaN; 477 * {@code false} otherwise. 478 */ isNaN(float v)479 public static boolean isNaN(float v) { 480 return (v != v); 481 } 482 483 /** 484 * Returns {@code true} if the specified number is infinitely 485 * large in magnitude, {@code false} otherwise. 486 * 487 * @param v the value to be tested. 488 * @return {@code true} if the argument is positive infinity or 489 * negative infinity; {@code false} otherwise. 490 */ isInfinite(float v)491 public static boolean isInfinite(float v) { 492 return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY); 493 } 494 495 496 /** 497 * Returns {@code true} if the argument is a finite floating-point 498 * value; returns {@code false} otherwise (for NaN and infinity 499 * arguments). 500 * 501 * @param f the {@code float} value to be tested 502 * @return {@code true} if the argument is a finite 503 * floating-point value, {@code false} otherwise. 504 * @since 1.8 505 */ isFinite(float f)506 public static boolean isFinite(float f) { 507 return Math.abs(f) <= Float.MAX_VALUE; 508 } 509 510 /** 511 * The value of the Float. 512 * 513 * @serial 514 */ 515 private final float value; 516 517 /** 518 * Constructs a newly allocated {@code Float} object that 519 * represents the primitive {@code float} argument. 520 * 521 * @param value the value to be represented by the {@code Float}. 522 * 523 * @deprecated 524 * It is rarely appropriate to use this constructor. The static factory 525 * {@link #valueOf(float)} is generally a better choice, as it is 526 * likely to yield significantly better space and time performance. 527 */ 528 @Deprecated(since="9", forRemoval = true) Float(float value)529 public Float(float value) { 530 this.value = value; 531 } 532 533 /** 534 * Constructs a newly allocated {@code Float} object that 535 * represents the argument converted to type {@code float}. 536 * 537 * @param value the value to be represented by the {@code Float}. 538 * 539 * @deprecated 540 * It is rarely appropriate to use this constructor. Instead, use the 541 * static factory method {@link #valueOf(float)} method as follows: 542 * {@code Float.valueOf((float)value)}. 543 */ 544 @Deprecated(since="9", forRemoval = true) Float(double value)545 public Float(double value) { 546 this.value = (float)value; 547 } 548 549 /** 550 * Constructs a newly allocated {@code Float} object that 551 * represents the floating-point value of type {@code float} 552 * represented by the string. The string is converted to a 553 * {@code float} value as if by the {@code valueOf} method. 554 * 555 * @param s a string to be converted to a {@code Float}. 556 * @throws NumberFormatException if the string does not contain a 557 * parsable number. 558 * 559 * @deprecated 560 * It is rarely appropriate to use this constructor. 561 * Use {@link #parseFloat(String)} to convert a string to a 562 * {@code float} primitive, or use {@link #valueOf(String)} 563 * to convert a string to a {@code Float} object. 564 */ 565 @Deprecated(since="9", forRemoval = true) Float(String s)566 public Float(String s) throws NumberFormatException { 567 value = parseFloat(s); 568 } 569 570 /** 571 * Returns {@code true} if this {@code Float} value is a 572 * Not-a-Number (NaN), {@code false} otherwise. 573 * 574 * @return {@code true} if the value represented by this object is 575 * NaN; {@code false} otherwise. 576 */ isNaN()577 public boolean isNaN() { 578 return isNaN(value); 579 } 580 581 /** 582 * Returns {@code true} if this {@code Float} value is 583 * infinitely large in magnitude, {@code false} otherwise. 584 * 585 * @return {@code true} if the value represented by this object is 586 * positive infinity or negative infinity; 587 * {@code false} otherwise. 588 */ isInfinite()589 public boolean isInfinite() { 590 return isInfinite(value); 591 } 592 593 /** 594 * Returns a string representation of this {@code Float} object. 595 * The primitive {@code float} value represented by this object 596 * is converted to a {@code String} exactly as if by the method 597 * {@code toString} of one argument. 598 * 599 * @return a {@code String} representation of this object. 600 * @see java.lang.Float#toString(float) 601 */ toString()602 public String toString() { 603 return Float.toString(value); 604 } 605 606 /** 607 * Returns the value of this {@code Float} as a {@code byte} after 608 * a narrowing primitive conversion. 609 * 610 * @return the {@code float} value represented by this object 611 * converted to type {@code byte} 612 * @jls 5.1.3 Narrowing Primitive Conversion 613 */ byteValue()614 public byte byteValue() { 615 return (byte)value; 616 } 617 618 /** 619 * Returns the value of this {@code Float} as a {@code short} 620 * after a narrowing primitive conversion. 621 * 622 * @return the {@code float} value represented by this object 623 * converted to type {@code short} 624 * @jls 5.1.3 Narrowing Primitive Conversion 625 * @since 1.1 626 */ shortValue()627 public short shortValue() { 628 return (short)value; 629 } 630 631 /** 632 * Returns the value of this {@code Float} as an {@code int} after 633 * a narrowing primitive conversion. 634 * 635 * @return the {@code float} value represented by this object 636 * converted to type {@code int} 637 * @jls 5.1.3 Narrowing Primitive Conversion 638 */ intValue()639 public int intValue() { 640 return (int)value; 641 } 642 643 /** 644 * Returns value of this {@code Float} as a {@code long} after a 645 * narrowing primitive conversion. 646 * 647 * @return the {@code float} value represented by this object 648 * converted to type {@code long} 649 * @jls 5.1.3 Narrowing Primitive Conversion 650 */ longValue()651 public long longValue() { 652 return (long)value; 653 } 654 655 /** 656 * Returns the {@code float} value of this {@code Float} object. 657 * 658 * @return the {@code float} value represented by this object 659 */ 660 @IntrinsicCandidate floatValue()661 public float floatValue() { 662 return value; 663 } 664 665 /** 666 * Returns the value of this {@code Float} as a {@code double} 667 * after a widening primitive conversion. 668 * 669 * @return the {@code float} value represented by this 670 * object converted to type {@code double} 671 * @jls 5.1.2 Widening Primitive Conversion 672 */ doubleValue()673 public double doubleValue() { 674 return (double)value; 675 } 676 677 /** 678 * Returns a hash code for this {@code Float} object. The 679 * result is the integer bit representation, exactly as produced 680 * by the method {@link #floatToIntBits(float)}, of the primitive 681 * {@code float} value represented by this {@code Float} 682 * object. 683 * 684 * @return a hash code value for this object. 685 */ 686 @Override hashCode()687 public int hashCode() { 688 return Float.hashCode(value); 689 } 690 691 /** 692 * Returns a hash code for a {@code float} value; compatible with 693 * {@code Float.hashCode()}. 694 * 695 * @param value the value to hash 696 * @return a hash code value for a {@code float} value. 697 * @since 1.8 698 */ hashCode(float value)699 public static int hashCode(float value) { 700 return floatToIntBits(value); 701 } 702 703 /** 704 * Compares this object against the specified object. The result 705 * is {@code true} if and only if the argument is not 706 * {@code null} and is a {@code Float} object that 707 * represents a {@code float} with the same value as the 708 * {@code float} represented by this object. For this 709 * purpose, two {@code float} values are considered to be the 710 * same if and only if the method {@link #floatToIntBits(float)} 711 * returns the identical {@code int} value when applied to 712 * each. 713 * 714 * <p>Note that in most cases, for two instances of class 715 * {@code Float}, {@code f1} and {@code f2}, the value 716 * of {@code f1.equals(f2)} is {@code true} if and only if 717 * 718 * <blockquote><pre> 719 * f1.floatValue() == f2.floatValue() 720 * </pre></blockquote> 721 * 722 * <p>also has the value {@code true}. However, there are two exceptions: 723 * <ul> 724 * <li>If {@code f1} and {@code f2} both represent 725 * {@code Float.NaN}, then the {@code equals} method returns 726 * {@code true}, even though {@code Float.NaN==Float.NaN} 727 * has the value {@code false}. 728 * <li>If {@code f1} represents {@code +0.0f} while 729 * {@code f2} represents {@code -0.0f}, or vice 730 * versa, the {@code equal} test has the value 731 * {@code false}, even though {@code 0.0f==-0.0f} 732 * has the value {@code true}. 733 * </ul> 734 * 735 * This definition allows hash tables to operate properly. 736 * 737 * @param obj the object to be compared 738 * @return {@code true} if the objects are the same; 739 * {@code false} otherwise. 740 * @see java.lang.Float#floatToIntBits(float) 741 */ equals(Object obj)742 public boolean equals(Object obj) { 743 return (obj instanceof Float) 744 && (floatToIntBits(((Float)obj).value) == floatToIntBits(value)); 745 } 746 747 /** 748 * Returns a representation of the specified floating-point value 749 * according to the IEEE 754 floating-point "single format" bit 750 * layout. 751 * 752 * <p>Bit 31 (the bit that is selected by the mask 753 * {@code 0x80000000}) represents the sign of the floating-point 754 * number. 755 * Bits 30-23 (the bits that are selected by the mask 756 * {@code 0x7f800000}) represent the exponent. 757 * Bits 22-0 (the bits that are selected by the mask 758 * {@code 0x007fffff}) represent the significand (sometimes called 759 * the mantissa) of the floating-point number. 760 * 761 * <p>If the argument is positive infinity, the result is 762 * {@code 0x7f800000}. 763 * 764 * <p>If the argument is negative infinity, the result is 765 * {@code 0xff800000}. 766 * 767 * <p>If the argument is NaN, the result is {@code 0x7fc00000}. 768 * 769 * <p>In all cases, the result is an integer that, when given to the 770 * {@link #intBitsToFloat(int)} method, will produce a floating-point 771 * value the same as the argument to {@code floatToIntBits} 772 * (except all NaN values are collapsed to a single 773 * "canonical" NaN value). 774 * 775 * @param value a floating-point number. 776 * @return the bits that represent the floating-point number. 777 */ 778 @IntrinsicCandidate floatToIntBits(float value)779 public static int floatToIntBits(float value) { 780 if (!isNaN(value)) { 781 return floatToRawIntBits(value); 782 } 783 return 0x7fc00000; 784 } 785 786 /** 787 * Returns a representation of the specified floating-point value 788 * according to the IEEE 754 floating-point "single format" bit 789 * layout, preserving Not-a-Number (NaN) values. 790 * 791 * <p>Bit 31 (the bit that is selected by the mask 792 * {@code 0x80000000}) represents the sign of the floating-point 793 * number. 794 * Bits 30-23 (the bits that are selected by the mask 795 * {@code 0x7f800000}) represent the exponent. 796 * Bits 22-0 (the bits that are selected by the mask 797 * {@code 0x007fffff}) represent the significand (sometimes called 798 * the mantissa) of the floating-point number. 799 * 800 * <p>If the argument is positive infinity, the result is 801 * {@code 0x7f800000}. 802 * 803 * <p>If the argument is negative infinity, the result is 804 * {@code 0xff800000}. 805 * 806 * <p>If the argument is NaN, the result is the integer representing 807 * the actual NaN value. Unlike the {@code floatToIntBits} 808 * method, {@code floatToRawIntBits} does not collapse all the 809 * bit patterns encoding a NaN to a single "canonical" 810 * NaN value. 811 * 812 * <p>In all cases, the result is an integer that, when given to the 813 * {@link #intBitsToFloat(int)} method, will produce a 814 * floating-point value the same as the argument to 815 * {@code floatToRawIntBits}. 816 * 817 * @param value a floating-point number. 818 * @return the bits that represent the floating-point number. 819 * @since 1.3 820 */ 821 @IntrinsicCandidate floatToRawIntBits(float value)822 public static native int floatToRawIntBits(float value); 823 824 /** 825 * Returns the {@code float} value corresponding to a given 826 * bit representation. 827 * The argument is considered to be a representation of a 828 * floating-point value according to the IEEE 754 floating-point 829 * "single format" bit layout. 830 * 831 * <p>If the argument is {@code 0x7f800000}, the result is positive 832 * infinity. 833 * 834 * <p>If the argument is {@code 0xff800000}, the result is negative 835 * infinity. 836 * 837 * <p>If the argument is any value in the range 838 * {@code 0x7f800001} through {@code 0x7fffffff} or in 839 * the range {@code 0xff800001} through 840 * {@code 0xffffffff}, the result is a NaN. No IEEE 754 841 * floating-point operation provided by Java can distinguish 842 * between two NaN values of the same type with different bit 843 * patterns. Distinct values of NaN are only distinguishable by 844 * use of the {@code Float.floatToRawIntBits} method. 845 * 846 * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three 847 * values that can be computed from the argument: 848 * 849 * <blockquote><pre>{@code 850 * int s = ((bits >> 31) == 0) ? 1 : -1; 851 * int e = ((bits >> 23) & 0xff); 852 * int m = (e == 0) ? 853 * (bits & 0x7fffff) << 1 : 854 * (bits & 0x7fffff) | 0x800000; 855 * }</pre></blockquote> 856 * 857 * Then the floating-point result equals the value of the mathematical 858 * expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-150</sup>. 859 * 860 * <p>Note that this method may not be able to return a 861 * {@code float} NaN with exactly same bit pattern as the 862 * {@code int} argument. IEEE 754 distinguishes between two 863 * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The 864 * differences between the two kinds of NaN are generally not 865 * visible in Java. Arithmetic operations on signaling NaNs turn 866 * them into quiet NaNs with a different, but often similar, bit 867 * pattern. However, on some processors merely copying a 868 * signaling NaN also performs that conversion. In particular, 869 * copying a signaling NaN to return it to the calling method may 870 * perform this conversion. So {@code intBitsToFloat} may 871 * not be able to return a {@code float} with a signaling NaN 872 * bit pattern. Consequently, for some {@code int} values, 873 * {@code floatToRawIntBits(intBitsToFloat(start))} may 874 * <i>not</i> equal {@code start}. Moreover, which 875 * particular bit patterns represent signaling NaNs is platform 876 * dependent; although all NaN bit patterns, quiet or signaling, 877 * must be in the NaN range identified above. 878 * 879 * @param bits an integer. 880 * @return the {@code float} floating-point value with the same bit 881 * pattern. 882 */ 883 @IntrinsicCandidate intBitsToFloat(int bits)884 public static native float intBitsToFloat(int bits); 885 886 /** 887 * Compares two {@code Float} objects numerically. There are 888 * two ways in which comparisons performed by this method differ 889 * from those performed by the Java language numerical comparison 890 * operators ({@code <, <=, ==, >=, >}) when 891 * applied to primitive {@code float} values: 892 * 893 * <ul><li> 894 * {@code Float.NaN} is considered by this method to 895 * be equal to itself and greater than all other 896 * {@code float} values 897 * (including {@code Float.POSITIVE_INFINITY}). 898 * <li> 899 * {@code 0.0f} is considered by this method to be greater 900 * than {@code -0.0f}. 901 * </ul> 902 * 903 * This ensures that the <i>natural ordering</i> of {@code Float} 904 * objects imposed by this method is <i>consistent with equals</i>. 905 * 906 * @param anotherFloat the {@code Float} to be compared. 907 * @return the value {@code 0} if {@code anotherFloat} is 908 * numerically equal to this {@code Float}; a value 909 * less than {@code 0} if this {@code Float} 910 * is numerically less than {@code anotherFloat}; 911 * and a value greater than {@code 0} if this 912 * {@code Float} is numerically greater than 913 * {@code anotherFloat}. 914 * 915 * @since 1.2 916 * @see Comparable#compareTo(Object) 917 */ compareTo(Float anotherFloat)918 public int compareTo(Float anotherFloat) { 919 return Float.compare(value, anotherFloat.value); 920 } 921 922 /** 923 * Compares the two specified {@code float} values. The sign 924 * of the integer value returned is the same as that of the 925 * integer that would be returned by the call: 926 * <pre> 927 * new Float(f1).compareTo(new Float(f2)) 928 * </pre> 929 * 930 * @param f1 the first {@code float} to compare. 931 * @param f2 the second {@code float} to compare. 932 * @return the value {@code 0} if {@code f1} is 933 * numerically equal to {@code f2}; a value less than 934 * {@code 0} if {@code f1} is numerically less than 935 * {@code f2}; and a value greater than {@code 0} 936 * if {@code f1} is numerically greater than 937 * {@code f2}. 938 * @since 1.4 939 */ compare(float f1, float f2)940 public static int compare(float f1, float f2) { 941 if (f1 < f2) 942 return -1; // Neither val is NaN, thisVal is smaller 943 if (f1 > f2) 944 return 1; // Neither val is NaN, thisVal is larger 945 946 // Cannot use floatToRawIntBits because of possibility of NaNs. 947 int thisBits = Float.floatToIntBits(f1); 948 int anotherBits = Float.floatToIntBits(f2); 949 950 return (thisBits == anotherBits ? 0 : // Values are equal 951 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN) 952 1)); // (0.0, -0.0) or (NaN, !NaN) 953 } 954 955 /** 956 * Adds two {@code float} values together as per the + operator. 957 * 958 * @param a the first operand 959 * @param b the second operand 960 * @return the sum of {@code a} and {@code b} 961 * @jls 4.2.4 Floating-Point Operations 962 * @see java.util.function.BinaryOperator 963 * @since 1.8 964 */ sum(float a, float b)965 public static float sum(float a, float b) { 966 return a + b; 967 } 968 969 /** 970 * Returns the greater of two {@code float} values 971 * as if by calling {@link Math#max(float, float) Math.max}. 972 * 973 * @param a the first operand 974 * @param b the second operand 975 * @return the greater of {@code a} and {@code b} 976 * @see java.util.function.BinaryOperator 977 * @since 1.8 978 */ max(float a, float b)979 public static float max(float a, float b) { 980 return Math.max(a, b); 981 } 982 983 /** 984 * Returns the smaller of two {@code float} values 985 * as if by calling {@link Math#min(float, float) Math.min}. 986 * 987 * @param a the first operand 988 * @param b the second operand 989 * @return the smaller of {@code a} and {@code b} 990 * @see java.util.function.BinaryOperator 991 * @since 1.8 992 */ min(float a, float b)993 public static float min(float a, float b) { 994 return Math.min(a, b); 995 } 996 997 /** 998 * Returns an {@link Optional} containing the nominal descriptor for this 999 * instance, which is the instance itself. 1000 * 1001 * @return an {@link Optional} describing the {@linkplain Float} instance 1002 * @since 12 1003 */ 1004 @Override describeConstable()1005 public Optional<Float> describeConstable() { 1006 return Optional.of(this); 1007 } 1008 1009 /** 1010 * Resolves this instance as a {@link ConstantDesc}, the result of which is 1011 * the instance itself. 1012 * 1013 * @param lookup ignored 1014 * @return the {@linkplain Float} instance 1015 * @since 12 1016 */ 1017 @Override resolveConstantDesc(MethodHandles.Lookup lookup)1018 public Float resolveConstantDesc(MethodHandles.Lookup lookup) { 1019 return this; 1020 } 1021 1022 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 1023 @java.io.Serial 1024 private static final long serialVersionUID = -2671257302660747028L; 1025 } 1026