libjava/java/io/StringWriter.java

   1 /* StringWriter.java -- Writes bytes to a StringBuffer
   2    Copyright (C) 1998, 1999, 2000, 2001, 2003 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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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 // Wow is this a dumb class.  CharArrayWriter can do all this and
  42 // more.  I would redirect all calls to one in fact, but the javadocs say
  43 // use a StringBuffer so I will comply.
  44
  45 /**
  46   * This class writes chars to an internal <code>StringBuffer</code> that
  47   * can then be used to retrieve a <code>String</code>.
  48   *
  49   * @author Aaron M. Renn (arenn@urbanophile.com)
  50   * @author Tom Tromey <tromey@cygnus.com>
  51   */
  52 public class StringWriter extends Writer
  53 {
  54   /**
  55    * This is the default size of the buffer if the user doesn't specify it.
  56    * @specnote The JCL Volume 1 says that 16 is the default size.
  57    */
  58   private static final int DEFAULT_BUFFER_SIZE = 16;
  59
  60   /**
  61    * This method closes the stream.  The contents of the internal buffer
  62    * can still be retrieved, but future writes are not guaranteed to work.
  63    */
  64   public void close () throws IOException
  65   {
  66     // JCL says this does nothing.  This seems to violate the Writer
  67     // contract, in that other methods should still throw an
  68     // IOException after a close.  Still, we just follow JCL.
  69   }
  70
  71   /**
  72    * This method flushes any buffered characters to the underlying output.
  73    * It does nothing in this class.
  74    */
  75   public void flush ()
  76   {
  77   }
  78
  79   /**
  80    * This method returns the <code>StringBuffer</code> object that this
  81    * object is writing to.  Note that this is the actual internal buffer, so
  82    * any operations performed on it will affect this stream object.
  83    *
  84    * @return The <code>StringBuffer</code> object being written to
  85    */
  86   public StringBuffer getBuffer ()
  87   {
  88     return buffer;
  89   }
  90
  91   /**
  92    * This method initializes a new <code>StringWriter</code> to write to a
  93    * <code>StringBuffer</code> initially sized to a default size of 16
  94    * chars.
  95    */
  96   public StringWriter ()
  97   {
  98     this (DEFAULT_BUFFER_SIZE);
  99   }
 100
 101   /**
 102    * This method initializes a new <code>StringWriter</code> to write to a
 103    * <code>StringBuffer</code> with the specified initial size.
 104    *
 105    * @param size The initial size to make the <code>StringBuffer</code>
 106    */
 107   public StringWriter (int size)
 108   {
 109     super ();
 110     buffer = new StringBuffer (size);
 111     lock = buffer;
 112   }
 113
 114   /**
 115    * This method returns the contents of the internal <code>StringBuffer</code>
 116    * as a <code>String</code>.
 117    *
 118    * @return A <code>String</code> representing the chars written to
 119    * this stream.
 120    */
 121   public String toString ()
 122   {
 123     return buffer.toString();
 124   }
 125
 126   /**
 127    * This method writes a single character to the output, storing it in
 128    * the internal buffer.
 129    *
 130    * @param oneChar The <code>char</code> to write, passed as an int.
 131    */
 132   public void write (int oneChar)
 133   {
 134     buffer.append((char) (oneChar & 0xFFFF));
 135   }
 136
 137   /**
 138    * This method writes <code>len</code> chars from the specified
 139    * array starting at index <code>offset</code> in that array to this
 140    * stream by appending the chars to the end of the internal buffer.
 141    *
 142    * @param chars The array of chars to write
 143    * @param offset The index into the array to start writing from
 144    * @param len The number of chars to write
 145    */
 146   public void write (char[] chars, int offset, int len)
 147   {
 148     buffer.append(chars, offset, len);
 149   }
 150
 151   /**
 152    * This method writes the characters in the specified <code>String</code>
 153    * to the stream by appending them to the end of the internal buffer.
 154    *
 155    * @param str The <code>String</code> to write to the stream.
 156    */
 157   public void write (String str)
 158   {
 159     buffer.append(str);
 160   }
 161
 162   /**
 163    * This method writes out <code>len</code> characters of the specified
 164    * <code>String</code> to the stream starting at character position
 165    * <code>offset</code> into the stream.  This is done by appending the
 166    * characters to the internal buffer.
 167    *
 168    * @param str The <code>String</code> to write characters from
 169    * @param offset The character position to start writing from
 170    * @param len The number of characters to write.
 171    */
 172   public void write (String str, int offset, int len)
 173   {
 174 //      char[] tmpbuf = new char[len];
 175 //      str.getChars(offset, offset+len, tmpbuf, 0);
 176 //      buf.append(tmpbuf, 0, tmpbuf.length);
 177     // This implementation assumes that String.substring is more
 178     // efficient than using String.getChars and copying the data
 179     // twice.  For libgcj, this is true.  For Classpath, it is not.
 180     // FIXME.
 181     buffer.append(str.substring(offset, offset + len));
 182   }
 183
 184   /**
 185    * This is the <code>StringBuffer</code> that we use to store bytes that
 186    * are written.
 187    */
 188   private StringBuffer buffer;
 189 }