java.io

Interface DataOutput

Known Subinterfaces:
ImageOutputStream, ObjectOutput
Known Implementing Classes:
BigEndianOutputStream, CorbaOutput, DataOutputStream, DefaultWriteObjectTester, FileCacheImageOutputStream, FileImageOutputStream, ImageOutputStreamImpl, MemoryCacheImageOutputStream, MidiDataOutputStream, ObjectOutputStream, RandomAccessFile, RMIMarshalledObjectOutputStream, RMIObjectOutputStream, SimpleSHSStream

public interface DataOutput

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 DataInput interface.
See Also:
DataInput

Method Summary

void
write(byte[] buf)
This method writes the raw byte array passed in to the output stream.
void
write(byte[] buf, int offset, int len)
This method writes raw bytes from the passed array buf starting offset bytes into the buffer.
void
write(int value)
This method writes an 8-bit value (passed into the method as a Java int) to an output stream.
void
writeBoolean(boolean value)
This method writes a Java boolean value to an output stream.
void
writeByte(int value)
This method writes a Java byte value to an output stream.
void
writeBytes(String value)
This method writes all the bytes in a String out to the stream.
void
writeChar(int value)
This method writes a Java char value to an output stream.
void
writeChars(String value)
This method writes all the characters of a String to an output stream as an array of char's.
void
writeDouble(double value)
This method writes a Java double value to the stream.
void
writeFloat(float value)
This method writes a Java float value to the stream.
void
writeInt(int value)
This method writes a Java int value to an output stream.
void
writeLong(long value)
This method writes a Java long value to an output stream.
void
writeShort(int value)
This method writes a Java short value to an output stream.
void
writeUTF(String value)
This method writes a Java String to the stream in a modified UTF-8 format.

Method Details

write

public void write(byte[] buf)
            throws IOException
This method writes the raw byte array passed in to the output stream.
Parameters:
buf - The byte array to write
Throws:
IOException - If an error occurs

write

public void write(byte[] buf,
                  int offset,
                  int len)
            throws IOException
This method writes raw bytes from the passed array buf starting offset bytes into the buffer. The number of bytes written will be exactly len.
Parameters:
buf - The buffer from which to write the data
offset - The offset into the buffer to start writing data from
len - The number of bytes to write from the buffer to the output stream
Throws:
IOException - If any other error occurs

write

public void write(int value)
            throws IOException
This method writes an 8-bit value (passed into the method as a Java int) to an output stream. The low 8 bits of the passed value are written.
Parameters:
value - The byte to write to the output stream
Throws:
IOException - If an error occurs

writeBoolean

public void writeBoolean(boolean value)
            throws IOException
This method writes a Java boolean value to an output stream. If value is true, 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 readBoolean method in DataInput.
Parameters:
value - The boolean value to write
Throws:
IOException - If an error occurs

writeByte

public void writeByte(int 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 int value passed. The value written can be read using the readByte or readUnsignedByte methods in DataInput.
Parameters:
value - The int value to write
Throws:
IOException - If an error occurs

writeBytes

public void writeBytes(String value)
            throws IOException
This method writes all the bytes in a String out to the stream. One byte is written for each character in the String. The high eight bits of each character are discarded, thus this method is inappropriate for completely representing Unicode characters.
Parameters:
value - The String to write
Throws:
IOException - If an error occurs

writeChar

public void writeChar(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 int value passed. These bytes will be written "big endian". That is, with the high byte written first in the following manner:

byte0 = (byte)((value & 0xFF00) >> 8);
byte1 = (byte)(value & 0x00FF);

The value written can be read using the readChar method in DataInput.

Parameters:
value - The char value to write
Throws:
IOException - If an error occurs

writeChars

public void writeChars(String value)
            throws IOException
This method writes all the characters of a String to an output stream as an array of char's. Each character is written using the method specified in the writeChar method.
Parameters:
value - The String to write
Throws:
IOException - If an error occurs

writeDouble

public void writeDouble(double value)
            throws IOException
This method writes a Java double value to the stream. This value is written by first calling the method Double.doubleToLongBits to retrieve an long representing the floating point number, then writing this long value to the stream exactly the same as the writeLong() method does. The value written can be read using the readDouble method in DataInput.
Parameters:
value - The double value to write
Throws:
IOException - If any other error occurs

writeFloat

public void writeFloat(float value)
            throws IOException
This method writes a Java float value to the stream. This value is written by first calling the method Float.floatToIntBits to retrieve an int representing the floating point number, then writing this int value to the stream exactly the same as the writeInt() method does. The value written can be read using the readFloat method in DataInput.
Parameters:
value - The float value to write
Throws:
IOException - If an error occurs

writeInt

public void writeInt(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:

byte0 = (byte)((value & 0xFF000000) >> 24);
byte1 = (byte)((value & 0x00FF0000) >> 16);
byte2 = (byte)((value & 0x0000FF00) >> 8);
byte3 = (byte)(value & 0x000000FF);

The value written can be read using the readInt method in DataInput.

Parameters:
value - The int value to write
Throws:
IOException - If an error occurs

writeLong

public void writeLong(long 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:

byte0 = (byte)((value & 0xFF00000000000000L) >> 56);
byte1 = (byte)((value & 0x00FF000000000000L) >> 48);
byte2 = (byte)((value & 0x0000FF0000000000L) >> 40);
byte3 = (byte)((value & 0x000000FF00000000L) >> 32);
byte4 = (byte)((value & 0x00000000FF000000L) >> 24);
byte5 = (byte)((value & 0x0000000000FF0000L) >> 16);
byte6 = (byte)((value & 0x000000000000FF00L) >> 8);
byte7 = (byte)(value & 0x00000000000000FFL);

The value written can be read using the readLong method in DataInput.

Parameters:
value - The long value to write
Throws:
IOException - If an error occurs

writeShort

public void writeShort(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 int value passed. These bytes will be written "big endian". That is, with the high byte written first in the following manner:

byte0 = (byte)((value & 0xFF00) >> 8);
byte1 = (byte)(value & 0x00FF);

The value written can be read using the readShort and readUnsignedShort methods in DataInput.

Parameters:
value - The int value to write as a 16-bit value
Throws:
IOException - If an error occurs

writeUTF

public void writeUTF(String value)
            throws IOException
This method writes a Java String 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 short value in the same manner used by the writeShort method. Note that this is the number of bytes in the encoded String not the String length. Next come the encoded characters. Each character in the String is encoded as either one, two or three bytes. For characters in the range of \u0001 to \u007F, one byte is used. The character value goes into bits 0-7 and bit eight is 0. For characters in the range of \u0080 to \u007FF, 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 \u0000. 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 readUTF method in DataInput.
Parameters:
value - The String to write
Throws:
IOException - If an error occurs

DataOutput.java -- Interface for writing data from a stream Copyright (C) 1998, 1999, 2001, 2003, 2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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.