001 /* StringWriter.java -- Writes bytes to a StringBuffer
002 Copyright (C) 1998, 1999, 2000, 2001, 2003, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.io;
040
041 // Wow is this a dumb class. CharArrayWriter can do all this and
042 // more. I would redirect all calls to one in fact, but the javadocs say
043 // use a StringBuffer so I will comply.
044
045 /**
046 * This class writes chars to an internal <code>StringBuffer</code> that
047 * can then be used to retrieve a <code>String</code>.
048 *
049 * @author Aaron M. Renn (arenn@urbanophile.com)
050 * @author Tom Tromey (tromey@cygnus.com)
051 */
052 public class StringWriter extends Writer
053 {
054 /**
055 * This is the default size of the buffer if the user doesn't specify it.
056 * @specnote The JCL Volume 1 says that 16 is the default size.
057 */
058 private static final int DEFAULT_BUFFER_SIZE = 16;
059
060 /**
061 * This method closes the stream. The contents of the internal buffer
062 * can still be retrieved, but future writes are not guaranteed to work.
063 *
064 * @exception IOException If an error orrurs.
065 */
066 public void close () throws IOException
067 {
068 // JCL says this does nothing. This seems to violate the Writer
069 // contract, in that other methods should still throw an
070 // IOException after a close. Still, we just follow JCL.
071 }
072
073 /**
074 * This method flushes any buffered characters to the underlying output.
075 * It does nothing in this class.
076 */
077 public void flush ()
078 {
079 }
080
081 /**
082 * This method returns the <code>StringBuffer</code> object that this
083 * object is writing to. Note that this is the actual internal buffer, so
084 * any operations performed on it will affect this stream object.
085 *
086 * @return The <code>StringBuffer</code> object being written to
087 */
088 public StringBuffer getBuffer ()
089 {
090 return buffer;
091 }
092
093 /**
094 * This method initializes a new <code>StringWriter</code> to write to a
095 * <code>StringBuffer</code> initially sized to a default size of 16
096 * chars.
097 */
098 public StringWriter ()
099 {
100 this (DEFAULT_BUFFER_SIZE);
101 }
102
103 /**
104 * This method initializes a new <code>StringWriter</code> to write to a
105 * <code>StringBuffer</code> with the specified initial size.
106 *
107 * @param size The initial size to make the <code>StringBuffer</code>
108 */
109 public StringWriter (int size)
110 {
111 super ();
112 buffer = new StringBuffer (size);
113 lock = buffer;
114 }
115
116 /**
117 * This method returns the contents of the internal <code>StringBuffer</code>
118 * as a <code>String</code>.
119 *
120 * @return A <code>String</code> representing the chars written to
121 * this stream.
122 */
123 public String toString ()
124 {
125 return buffer.toString();
126 }
127
128 /**
129 * This method writes a single character to the output, storing it in
130 * the internal buffer.
131 *
132 * @param oneChar The <code>char</code> to write, passed as an int.
133 */
134 public void write (int oneChar)
135 {
136 buffer.append((char) (oneChar & 0xFFFF));
137 }
138
139 /**
140 * This method writes <code>len</code> chars from the specified
141 * array starting at index <code>offset</code> in that array to this
142 * stream by appending the chars to the end of the internal buffer.
143 *
144 * @param chars The array of chars to write
145 * @param offset The index into the array to start writing from
146 * @param len The number of chars to write
147 */
148 public void write (char[] chars, int offset, int len)
149 {
150 buffer.append(chars, offset, len);
151 }
152
153 /**
154 * This method writes the characters in the specified <code>String</code>
155 * to the stream by appending them to the end of the internal buffer.
156 *
157 * @param str The <code>String</code> to write to the stream.
158 */
159 public void write (String str)
160 {
161 buffer.append(str);
162 }
163
164 /**
165 * This method writes out <code>len</code> characters of the specified
166 * <code>String</code> to the stream starting at character position
167 * <code>offset</code> into the stream. This is done by appending the
168 * characters to the internal buffer.
169 *
170 * @param str The <code>String</code> to write characters from
171 * @param offset The character position to start writing from
172 * @param len The number of characters to write.
173 */
174 public void write (String str, int offset, int len)
175 {
176 // char[] tmpbuf = new char[len];
177 // str.getChars(offset, offset+len, tmpbuf, 0);
178 // buf.append(tmpbuf, 0, tmpbuf.length);
179 // This implementation assumes that String.substring is more
180 // efficient than using String.getChars and copying the data
181 // twice. For libgcj, this is true. For Classpath, it is not.
182 // FIXME.
183 buffer.append(str.substring(offset, offset + len));
184 }
185
186 /** @since 1.5 */
187 public StringWriter append(char c)
188 {
189 write(c);
190 return this;
191 }
192
193 /** @since 1.5 */
194 public StringWriter append(CharSequence cs)
195 {
196 write(cs == null ? "null" : cs.toString());
197 return this;
198 }
199
200 /** @since 1.5 */
201 public StringWriter append(CharSequence cs, int start, int end)
202 {
203 write(cs == null ? "null" : cs.subSequence(start, end).toString());
204 return this;
205 }
206
207 /**
208 * This is the <code>StringBuffer</code> that we use to store bytes that
209 * are written.
210 */
211 private StringBuffer buffer;
212 }