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    }