libjava/java/io/OutputStream.java

   1 /* OutputStream.java -- Base class for byte output streams
   2    Copyright (C) 1998, 1999, 2001, 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., 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 /**
  42   * This abstract class forms the base of the hierarchy of classes that
  43   * write output as a stream of bytes.  It provides a common set of methods
  44   * for writing bytes to stream.  Subclasses implement and/or extend these
  45   * methods to write bytes in a particular manner or to a particular
  46   * destination such as a file on disk or network connection.
  47   *
  48   * @author Aaron M. Renn (arenn@urbanophile.com)
  49   * @author Tom Tromey (tromey@cygnus.com)
  50   */
  51 public abstract class OutputStream
  52 {
  53   /**
  54    * This is the default no-argument constructor for this class.  This method
  55    * does nothing in this class.
  56    */
  57   public OutputStream ()
  58   {
  59   }
  60
  61   /**
  62    * This method writes a single byte to the output stream.  The byte written
  63    * is the low eight bits of the <code>int</code> passed and a argument.
  64    * <p>
  65    * Subclasses must provide an implementation of this abstract method
  66    *
  67    * @param b The byte to be written to the output stream, passed as
  68    *          the low eight bits of an <code>int</code>
  69    *
  70    * @exception IOException If an error occurs
  71    */
  72   public abstract void write (int b) throws IOException;
  73
  74   /**
  75    * This method all the writes bytes from the passed array to the
  76    * output stream.  This method is equivalent to <code>write(b, 0,
  77    * buf.length)</code> which is exactly how it is implemented in this
  78    * class.
  79    *
  80    * @param b The array of bytes to write
  81    *
  82    * @exception IOException If an error occurs
  83    */
  84   public void write (byte[] b) throws IOException, NullPointerException
  85   {
  86     write (b, 0, b.length);
  87   }
  88
  89   /**
  90    * This method writes <code>len</code> bytes from the specified array
  91    * <code>b</code> starting at index <code>off</code> into the array.
  92    * <p>
  93    * This method in this class calls the single byte <code>write()</code>
  94    * method in a loop until all bytes have been written.  Subclasses should
  95    * override this method if possible in order to provide a more efficent
  96    * implementation.
  97    *
  98    * @param b The array of bytes to write from
  99    * @param off The index into the array to start writing from
 100    * @param len The number of bytes to write
 101    *
 102    * @exception IOException If an error occurs
 103    */
 104   public void write (byte[] b, int off, int len)
 105     throws IOException, NullPointerException, IndexOutOfBoundsException
 106   {
 107     if (off < 0 || len < 0 || off + len > b.length)
 108       throw new ArrayIndexOutOfBoundsException ();
 109     for (int i = 0; i < len; ++i)
 110       write (b[off + i]);
 111   }
 112
 113   /**
 114    * This method forces any data that may have been buffered to be written
 115    * to the underlying output device.  Please note that the host environment
 116    * might perform its own buffering unbeknowst to Java.  In that case, a
 117    * write made (for example, to a disk drive) might be cached in OS
 118    * buffers instead of actually being written to disk.
 119    * <p>
 120    * This method in this class does nothing.
 121    *
 122    * @exception IOException If an error occurs
 123    */
 124   public void flush () throws IOException
 125   {
 126   }
 127
 128   /**
 129    * This method closes the stream.  Any internal or native resources
 130    * associated with this stream are freed.  Any subsequent attempt to
 131    * access the stream might throw an exception.
 132    * <p>
 133    * This method in this class does nothing.
 134    *
 135    * @exception IOException If an error occurs
 136    */
 137   public void close () throws IOException
 138   {
 139   }
 140 }