gcc/libjava/java/io/DataOutput.java

/* DataOutput.java -- Interface for writing data from a stream
   Copyright (C) 1998, 1999, 2001, 2003 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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package java.io;

/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
 * "The Java Language Specification", ISBN 0-201-63451-1
 * Status:  Complete to version 1.1.
 */

/**
 * This interface is implemented by classes that can wrte data to streams 
 * from Java primitive types.  This data can subsequently be read back
 * by classes implementing the <code>DataInput</code> interface. 
 *
 * @author Aaron M. Renn (arenn@urbanophile.com)
 * @author Tom Tromey <tromey@cygnus.com>
 *
 * @see DataInput
 */
public interface DataOutput
{
  /**
   * This method writes a Java boolean value to an output stream.  If
   * <code>value</code> is <code>true</code>, a byte with the value of
   * 1 will be written, otherwise a byte with the value of 0 will be 
   * written.
   *
   * The value written can be read using the <code>readBoolean</code>
   * method in <code>DataInput</code>.
   *
   * @param value The boolean value to write
   *
   * @exception IOException If an error occurs
   *
   * @see DataInput#readBoolean
   */
  void writeBoolean(boolean value) throws IOException;

  /**
   * This method writes a Java byte value to an output stream.  The
   * byte to be written will be in the lowest 8 bits of the 
   * <code>int</code> value passed.
   *
   * The value written can be read using the <code>readByte</code> or
   * <code>readUnsignedByte</code> methods in <code>DataInput</code>.
   *
   * @param value The int value to write
   *
   * @exception IOException If an error occurs
   *
   * @see DataInput#readByte
   * @see DataInput#readUnsignedByte
   */
  void writeByte(int value) throws IOException;

  /**
   * This method writes a Java char value to an output stream.  The
   * char to be written will be in the lowest 16 bits of the <code>int</code>
   * value passed.  These bytes will be written "big endian".  That is,
   * with the high byte written first in the following manner:
   * <p>
   * <code>byte0 = (byte)((value & 0xFF00) >> 8);<br>
   * byte1 = (byte)(value & 0x00FF);</code>
   * <p>
   *
   * The value written can be read using the <code>readChar</code>
   * method in <code>DataInput</code>.
   *
   * @param value The char value to write
   *
   * @exception IOException If an error occurs
   *
   * @see DataInput#readChar
   */
  void writeChar(int value) throws IOException;

  /**
   * This method writes a Java short value to an output stream.  The
   * char to be written will be in the lowest 16 bits of the <code>int</code>
   * value passed.  These bytes will be written "big endian".  That is,
   * with the high byte written first in the following manner:
   * <p>
   * <code>byte0 = (byte)((value & 0xFF00) >> 8);<br>
   * byte1 = (byte)(value & 0x00FF);</code>
   * <p>
   *
   * The value written can be read using the <code>readShort</code> and
   * <code>readUnsignedShort</code> methods in <code>DataInput</code>.
   *
   * @param value The int value to write as a 16-bit value
   *
   * @exception IOException If an error occurs
   *
   * @see DataInput#readShort
   * @see DataInput#readUnsignedShort
   */
  void writeShort(int value) throws IOException;

  /**
   * This method writes a Java int value to an output stream.  The 4 bytes
   * of the passed value will be written "big endian".  That is, with
   * the high byte written first in the following manner:
   * <p>
   * <code>byte0 = (byte)((value & 0xFF000000) >> 24);<br>
   * byte1 = (byte)((value & 0x00FF0000) >> 16);<br>
   * byte2 = (byte)((value & 0x0000FF00) >> 8);<br>
   * byte3 = (byte)(value & 0x000000FF);</code>
   * <p>
   *
   * The value written can be read using the <code>readInt</code>
   * method in <code>DataInput</code>.
   *
   * @param value The int value to write
   *
   * @exception IOException If an error occurs
   *
   * @see DataInput#readInt
   */
  void writeInt(int value) throws IOException;

  /**
   * This method writes a Java long value to an output stream.  The 8 bytes
   * of the passed value will be written "big endian".  That is, with
   * the high byte written first in the following manner:
   * <p>
   * <code>byte0 = (byte)((value & 0xFF00000000000000L) >> 56);<br>
   * byte1 = (byte)((value & 0x00FF000000000000L) >> 48);<br>
   * byte2 = (byte)((value & 0x0000FF0000000000L) >> 40);<br>
   * byte3 = (byte)((value & 0x000000FF00000000L) >> 32);<br>
   * byte4 = (byte)((value & 0x00000000FF000000L) >> 24);<br>
   * byte5 = (byte)((value & 0x0000000000FF0000L) >> 16);<br>
   * byte6 = (byte)((value & 0x000000000000FF00L) >> 8);<br>
   * byte7 = (byte)(value & 0x00000000000000FFL);</code>
   * <p>
   *
   * The value written can be read using the <code>readLong</code>
   * method in <code>DataInput</code>.
   *
   * @param value The long value to write
   *
   * @exception IOException If an error occurs
   *
   * @see DataInput#readLong
   */
  void writeLong(long value) throws IOException;

  /**
   * This method writes a Java <code>float</code> value to the stream.  This
   * value is written by first calling the method
   * <code>Float.floatToIntBits</code>
   * to retrieve an <code>int</code> representing the floating point number,
   * then writing this <code>int</code> value to the stream exactly the same
   * as the <code>writeInt()</code> method does.
   *
   * The value written can be read using the <code>readFloat</code>
   * method in <code>DataInput</code>.
   *
   * @param value The float value to write
   *
   * @exception IOException If an error occurs
   *
   * @see writeInt
   * @see DataInput#readFloat
   * @see Float#floatToIntBits
   */
  void writeFloat(float value) throws IOException;

  /**
   * This method writes a Java <code>double</code> value to the stream.  This
   * value is written by first calling the method
   * <code>Double.doubleToLongBits</code>
   * to retrieve an <code>long</code> representing the floating point number,
   * then writing this <code>long</code> value to the stream exactly the same
   * as the <code>writeLong()</code> method does.
   *
   * The value written can be read using the <code>readDouble</code>
   * method in <code>DataInput</code>.
   *
   * @param value The double value to write
   *
   * @exception IOException If any other error occurs
   *
   * @see writeLong
   * @see DataInput#readDouble
   * @see Double#doubleToLongBits
   */
  void writeDouble(double value) throws IOException;

  /**
   * This method writes all the bytes in a <code>String</code> out to the
   * stream.  One byte is written for each character in the
   * <code>String</code>.
   * The high eight bits of each character are discarded, thus this
   * method is inappropriate for completely representing Unicode characters.
   *
   * @param value The <code>String</code> to write
   *
   * @exception IOException If an error occurs
   */
  void writeBytes(String value) throws IOException;

  /**
   * This method writes all the characters of a <code>String</code> to an 
   * output stream as an array of <code>char</code>'s. Each character
   * is written using the method specified in the <code>writeChar</code>
   * method. 
   *
   * @param value The String to write
   *
   * @exception IOException If an error occurs
   *
   * @see writeChar
   */
  void writeChars(String value) throws IOException;

  /**
  * This method writes a Java <code>String</code> to the stream in a modified
   * UTF-8 format.  First, two bytes are written to the stream indicating the
   * number of bytes to follow.  This is written in the form of a Java
   * <code>short</code> value in the same manner used by the 
   * <code>writeShort</code> method.  Note that this is the number of 
   * bytes in the
   * encoded <code>String</code> not the <code>String</code> length.  Next
   * come the encoded characters.  Each character in the <code>String</code>
   * is encoded as either one, two or three bytes.  For characters in the
   * range of <code>\u0001</code> to <code>\u007F</code>, one byte is used.  
   * The character
   * value goes into bits 0-7 and bit eight is 0.  For characters in the range
   * of <code>\u0080</code> to <code>\u007FF</code>, two bytes are used.  Bits
   * 6-10 of the character value are encoded bits 0-4 of the first byte, with
   * the high bytes having a value of "110".  Bits 0-5 of the character value
   * are stored in bits 0-5 of the second byte, with the high bits set to
   * "10".  This type of encoding is also done for the null character
   * <code>\u0000</code>.  This eliminates any C style NUL character values
   * in the output.  All remaining characters are stored as three bytes.
   * Bits 12-15 of the character value are stored in bits 0-3 of the first
   * byte.  The high bits of the first bytes are set to "1110".  Bits 6-11
   * of the character value are stored in bits 0-5 of the second byte.  The
   * high bits of the second byte are set to "10".  And bits 0-5 of the
   * character value are stored in bits 0-5 of byte three, with the high bits
   * of that byte set to "10".
   *
   * The value written can be read using the <code>readUTF</code>
   * method in <code>DataInput</code>.
   *
   * @param value The <code>String</code> to write
   *
   * @exception IOException If an error occurs
   *
   * @see DataInput#readUTF
   */
  void writeUTF(String value) throws IOException;

  /**
   * This method writes an 8-bit value (passed into the method as a Java
   * <code>int</code>) to an output stream.  The low 8 bits of the
   * passed value are written.
   *
   * @param value The <code>byte</code> to write to the output stream
   *
   * @exception IOException If an error occurs
   */
  void write(int value) throws IOException;

  /**
   * This method writes the raw byte array passed in to the output stream.
   *
   * @param buf The byte array to write
   *
   * @exception IOException If an error occurs
   */
  void write(byte[] buf) throws IOException;

  /**
   * This method writes raw bytes from the passed array <code>buf</code> 
   * starting
   * <code>offset</code> bytes into the buffer.  The number of bytes 
   * written will be exactly <code>len</code>. 
   *
   * @param buf The buffer from which to write the data
   * @param offset The offset into the buffer to start writing data from
   * @param len The number of bytes to write from the buffer to the output 
   * stream
   *
   * @exception IOException If any other error occurs
   */
  void write(byte[] buf, int offset, int len) throws IOException;

} // interface DataOutput