datainput.java

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/* DataInput.java -- Interface for reading data from a stream
   Copyright (C) 1998, 1999, 2001 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.

You should have received a copy of the GNU General Public License
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
conditions of the GNU General Public License cover the whole
combination.

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
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package java.io;

/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
 * "The Java Language Specification", ISBN 0-201-63451-1
 * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
 * Status:  Believed complete and correct.
 */

/**
  * This interface is implemented by classes that can data from streams 
  * into Java primitive types. 
  *
  * @author Aaron M. Renn ([e-mail])
  * @author Warren Levy <[e-mail]>
  */
public interface DataInput
{

/**
  * This method reads a Java boolean value from an input stream.  It does
  * so by reading a single byte of data.  If that byte is zero, then the
  * value returned is <code>false</code>.  If the byte is non-zero, then
  * the value returned is <code>true</code>.
  * <p>
  * This method can read a <code>boolean</code> written by an object
  * implementing the <code>writeBoolean()</code> method in the
  * <code>DataOutput</code> interface.
  *
  * @return The <code>boolean</code> value read
  *
  * @exception EOFException If end of file is reached before reading the boolean
  * @exception IOException If any other error occurs
  */
boolean
readBoolean() throws EOFException, IOException;

/*************************************************************************/

/**
  * This method reads a Java byte value from an input stream.  The value
  * is in the range of -128 to 127.
  * <p>
  * This method can read a <code>byte</code> written by an object
  * implementing the 
  * <code>writeByte()</code> method in the <code>DataOutput</code> interface.
  * <p>
  * @return The <code>byte</code> value read
  *
  * @exception EOFException If end of file is reached before reading the byte
  * @exception IOException If any other error occurs
  *
  * @see DataOutput
  */
byte
readByte() throws EOFException, IOException;

/*************************************************************************/

/**
  * This method reads 8 unsigned bits into a Java <code>int</code> value from
  * the stream. The value returned is in the range of 0 to 255.
  * <p>
  * This method can read an unsigned byte written by an object implementing the
  * <code>writeUnsignedByte()</code> method in the <code>DataOutput</code>
  * interface.
  *
  * @return The unsigned bytes value read as a Java <code>int</code>.
  *
  * @exception EOFException If end of file is reached before reading the value
  * @exception IOException If any other error occurs
  *
  * @see DataOutput
  */
int
readUnsignedByte() throws EOFException, IOException;

/*************************************************************************/

/**
  * This method reads a Java <code>char</code> value from an input stream.  
  * It operates by reading two bytes from the stream and converting them to 
  * a single 16-bit Java <code>char</code>.  The two bytes are stored most
  * significant byte first (i.e., "big endian") regardless of the native
  * host byte ordering. 
  * <p>
  * As an example, if <code>byte1</code> and <code>byte2</code> represent the
  * first and second byte read from the stream respectively, they will be
  * transformed to a <code>char</code> in the following manner:
  * <p>
  * <code>(char)((byte1 << 8) + byte2)</code>
  * <p>
  * This method can read a <code>char</code> written by an object implementing
  * the
  * <code>writeChar()</code> method in the <code>DataOutput</code> interface.
  *
  * @return The <code>char</code> value read 
  *
  * @exception EOFException If end of file is reached before reading the char
  * @exception IOException If any other error occurs
  *
  * @see DataOutput
  */
char
readChar() throws EOFException, IOException;

/*************************************************************************/

/**
  * This method reads a signed 16-bit value into a Java in from the stream.
  * It operates by reading two bytes from the stream and converting them to 
  * a single 16-bit Java <code>short</code>.  The two bytes are stored most
  * significant byte first (i.e., "big endian") regardless of the native
  * host byte ordering. 
  * <p>
  * As an example, if <code>byte1</code> and <code>byte2</code> represent the
  * first and second byte read from the stream respectively, they will be
  * transformed to a <code>short</code> in the following manner:
  * <p>
  * <code>(short)((byte1 << 8) + byte2)</code>
  * <p>
  * The value returned is in the range of -32768 to 32767.
  * <p>
  * This method can read a <code>short</code> written by an object implementing
  * the <code>writeShort()</code> method in the <code>DataOutput</code>
  * interface.
  *
  * @return The <code>short</code> value read
  *
  * @exception EOFException If end of file is reached before reading the value
  * @exception IOException If any other error occurs
  *
  * @see DataOutput
  */
short
readShort() throws EOFException, IOException;

/*************************************************************************/

/**
  * This method reads 16 unsigned bits into a Java int value from the stream.
  * It operates by reading two bytes from the stream and converting them to 
  * a single Java <code>int</code>.  The two bytes are stored most
  * significant byte first (i.e., "big endian") regardless of the native
  * host byte ordering. 
  * <p>
  * As an example, if <code>byte1</code> and <code>byte2</code> represent the
  * first and second byte read from the stream respectively, they will be
  * transformed to an <code>int</code> in the following manner:
  * <p>
  * <code>(int)((byte1 << 8) + byte2)</code>
  * <p>
  * The value returned is in the range of 0 to 65535.
  * <p>
  * This method can read an unsigned short written by an object implementing
  * the <code>writeUnsignedShort()</code> method in the <code>DataOutput</code>
  * interface.
  *
  * @return The unsigned short value read as a Java <code>int</code>.
  *
  * @exception EOFException If end of file is reached before reading the value
  * @exception IOException If any other error occurs
  */
int
readUnsignedShort() throws EOFException, IOException;

/*************************************************************************/

/**
  * This method reads a Java <code>int</code> value from an input stream
  * It operates by reading four bytes from the stream and converting them to 
  * a single Java <code>int</code>.  The bytes are stored most
  * significant byte first (i.e., "big endian") regardless of the native
  * host byte ordering. 
  * <p>
  * As an example, if <code>byte1</code> through <code>byte4</code> represent
  * the first four bytes read from the stream, they will be
  * transformed to an <code>int</code> in the following manner:
  * <p>
  * <code>(int)((byte1 << 24) + (byte2 << 16) + (byte3 << 8) + byte4))</code>
  * <p>
   The value returned is in the range of -2147483648 to 2147483647.
  * <p>
  * This method can read an <code>int</code> written by an object implementing
  * the <code>writeInt()</code> method in the <code>DataOutput</code> interface.
  *
  * @return The <code>int</code> value read
  *
  * @exception EOFException If end of file is reached before reading the int
  * @exception IOException If any other error occurs
  *
  * @see DataOutput
  */
int
readInt() throws EOFException, IOException;

/*************************************************************************/

/**
  * This method reads a Java <code>long</code> value from an input stream