1 /* Writer.java -- Base class for character output streams 2 Copyright (C) 1998, 1999, 2001, 2003, 2004, 2005 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package java.io; 40 41 /* Written using "Java Class Libraries", 2nd edition, plus online 42 * API docs for JDK 1.2 beta from http://www.javasoft.com. 43 * Status: Believed complete and correct. 44 */ 45 46 /** 47 * This abstract class forms the base of the hierarchy of classes that 48 * write output as a stream of chars. It provides a common set of methods 49 * for writing chars to stream. Subclasses implement and/or extend these 50 * methods to write chars in a particular manner or to a particular 51 * destination such as a file on disk or network connection. 52 * 53 * @author Aaron M. Renn (arenn@urbanophile.com) 54 * @author Per Bothner (bothner@cygnus.com) 55 */ 56 public abstract class Writer implements Appendable, Closeable, Flushable 57 { 58 /** 59 * This is the object used to synchronize criticial code sections for 60 * thread safety. Subclasses should use this field instead of using 61 * synchronized methods or explicity synchronizations on <code>this</code> 62 */ 63 protected Object lock; 64 65 /** 66 * This is the default no-argument constructor for this class. This method 67 * will set up the class to synchronize criticial sections on itself. 68 */ Writer()69 protected Writer() 70 { 71 lock = this; 72 } 73 74 /** 75 * This method initializes a <code>Writer</code> that will synchronize 76 * on the specified <code>Object</code>. 77 * 78 * @param lock The <code>Object</code> to use for synchronizing critical 79 * sections. Must not be null. 80 */ Writer(Object lock)81 protected Writer(Object lock) 82 { 83 if (lock == null) 84 throw new NullPointerException(); 85 86 this.lock = lock; 87 } 88 89 /** 90 * This method forces any data that may have been buffered to be written 91 * to the underlying output device. Please note that the host environment 92 * might perform its own buffering unbeknowst to Java. In that case, a 93 * write made (for example, to a disk drive) might be cached in OS 94 * buffers instead of actually being written to disk. 95 * 96 * @exception IOException If an error occurs 97 */ flush()98 public abstract void flush() throws IOException; 99 100 /** 101 * This method closes the stream. Any internal or native resources 102 * associated 103 * with this stream are freed. Any subsequent attempt to access the stream 104 * might throw an exception. 105 * <p> 106 * This method in this class does nothing. 107 * 108 * @exception IOException If an error occurs 109 */ close()110 public abstract void close() throws IOException; 111 112 /** 113 * This method writes a single char to the output stream. 114 * 115 * @param b The char to be written to the output stream, passed as an int 116 * 117 * @exception IOException If an error occurs 118 */ write(int b)119 public void write(int b) throws IOException 120 { 121 char[] buf = new char[1]; 122 123 buf[0] = (char)b; 124 write(buf, 0, buf.length); 125 } 126 127 /** 128 * This method all the writes char from the passed array to the output 129 * stream. This method is equivalent to 130 * <code>write(buf, 0, buf.length)</code> which 131 * is exactly how it is implemented in this class. 132 * 133 * @param buf The array of char to write 134 * 135 * @exception IOException If an error occurs 136 */ write(char[] buf)137 public void write(char[] buf) throws IOException 138 { 139 write(buf, 0, buf.length); 140 } 141 142 /** 143 * This method writes <code>len</code> char from the specified array 144 * <code>buf</code> starting at index <code>offset</code> into the array. 145 * <p> 146 * Subclasses must provide an implementation of this abstract method. 147 * 148 * @param buf The array of char to write from 149 * @param offset The index into the array to start writing from 150 * @param len The number of char to write 151 * 152 * @exception IOException If an error occurs 153 */ write(char[] buf, int offset, int len)154 public abstract void write(char[] buf, int offset, int len) 155 throws IOException; 156 157 /** 158 * This method writes all the characters in a <code>String</code> to the 159 * output. 160 * 161 * @param str The <code>String</code> whose chars are to be written. 162 * 163 * @exception IOException If an error occurs 164 */ write(String str)165 public void write(String str) throws IOException 166 { 167 write(str, 0, str.length()); 168 } 169 170 /** 171 * This method writes <code>len</code> chars from the <code>String</code> 172 * starting at position <code>offset</code>. 173 * 174 * @param str The <code>String</code> that is to be written 175 * @param offset The character offset into the <code>String</code> to start 176 * writing from 177 * @param len The number of chars to write 178 * 179 * @exception IOException If an error occurs 180 */ write(String str, int offset, int len)181 public void write(String str, int offset, int len) throws IOException 182 { 183 // FIXME - for libgcj re-write using native code to not require 184 // copied buffer. 185 char[] buf = new char[len]; 186 187 str.getChars(offset, offset + len, buf, 0); 188 write(buf, 0, len); 189 } 190 191 /** @since 1.5 */ append(char c)192 public Writer append(char c) throws IOException 193 { 194 write(c); 195 return this; 196 } 197 198 /** @since 1.5 */ append(CharSequence cs)199 public Writer append(CharSequence cs) throws IOException 200 { 201 write(cs == null ? "null" : cs.toString()); 202 return this; 203 } 204 205 /** @since 1.5 */ append(CharSequence cs, int start, int end)206 public Writer append(CharSequence cs, int start, int end) throws IOException 207 { 208 write(cs == null ? "null" : cs.subSequence(start, end).toString()); 209 return this; 210 } 211 } 212