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OutputStream.javaAPI DocJava SE 5 API5514Fri Aug 26 14:57:00 BST 2005java.io

OutputStream.java

/*
 * @(#)OutputStream.java	1.29 04/04/21
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.io;

/**
 * This abstract class is the superclass of all classes representing 
 * an output stream of bytes. An output stream accepts output bytes 
 * and sends them to some sink.
 * <p>
 * Applications that need to define a subclass of 
 * <code>OutputStream</code> must always provide at least a method 
 * that writes one byte of output.
 *
 * @author  Arthur van Hoff
 * @version 1.29, 04/21/04
 * @see     java.io.BufferedOutputStream
 * @see     java.io.ByteArrayOutputStream
 * @see     java.io.DataOutputStream
 * @see     java.io.FilterOutputStream
 * @see     java.io.InputStream
 * @see     java.io.OutputStream#write(int)
 * @since   JDK1.0
 */
public abstract class OutputStream implements Closeable, Flushable {
    /**
     * Writes the specified byte to this output stream. The general 
     * contract for <code>write</code> is that one byte is written 
     * to the output stream. The byte to be written is the eight 
     * low-order bits of the argument <code>b</code>. The 24 
     * high-order bits of <code>b</code> are ignored.
     * <p>
     * Subclasses of <code>OutputStream</code> must provide an 
     * implementation for this method. 
     *
     * @param      b   the <code>byte</code>.
     * @exception  IOException  if an I/O error occurs. In particular, 
     *             an <code>IOException</code> may be thrown if the 
     *             output stream has been closed.
     */
    public abstract void write(int b) throws IOException;

    /**
     * Writes <code>b.length</code> bytes from the specified byte array 
     * to this output stream. The general contract for <code>write(b)</code> 
     * is that it should have exactly the same effect as the call 
     * <code>write(b, 0, b.length)</code>.
     *
     * @param      b   the data.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.OutputStream#write(byte[], int, int)
     */
    public void write(byte b[]) throws IOException {
	write(b, 0, b.length);
    }

    /**
     * Writes <code>len</code> bytes from the specified byte array 
     * starting at offset <code>off</code> to this output stream. 
     * The general contract for <code>write(b, off, len)</code> is that 
     * some of the bytes in the array <code>b</code> are written to the 
     * output stream in order; element <code>b[off]</code> is the first 
     * byte written and <code>b[off+len-1]</code> is the last byte written 
     * by this operation.
     * <p>
     * The <code>write</code> method of <code>OutputStream</code> calls 
     * the write method of one argument on each of the bytes to be 
     * written out. Subclasses are encouraged to override this method and 
     * provide a more efficient implementation. 
     * <p>
     * If <code>b</code> is <code>null</code>, a 
     * <code>NullPointerException</code> is thrown.
     * <p>
     * If <code>off</code> is negative, or <code>len</code> is negative, or 
     * <code>off+len</code> is greater than the length of the array 
     * <code>b</code>, then an <tt>IndexOutOfBoundsException</tt> is thrown.
     *
     * @param      b     the data.
     * @param      off   the start offset in the data.
     * @param      len   the number of bytes to write.
     * @exception  IOException  if an I/O error occurs. In particular, 
     *             an <code>IOException</code> is thrown if the output 
     *             stream is closed.
     */
    public void write(byte b[], int off, int len) throws IOException {
	if (b == null) {
	    throw new NullPointerException();
	} else if ((off < 0) || (off > b.length) || (len < 0) ||
		   ((off + len) > b.length) || ((off + len) < 0)) {
	    throw new IndexOutOfBoundsException();
	} else if (len == 0) {
	    return;
	}
	for (int i = 0 ; i < len ; i++) {
	    write(b[off + i]);
	}
    }

    /**
     * Flushes this output stream and forces any buffered output bytes 
     * to be written out. The general contract of <code>flush</code> is 
     * that calling it is an indication that, if any bytes previously 
     * written have been buffered by the implementation of the output 
     * stream, such bytes should immediately be written to their 
     * intended destination.
     * <p>
     * If the intended destination of this stream is an abstraction provided by
     * the underlying operating system, for example a file, then flushing the
     * stream guarantees only that bytes previously written to the stream are
     * passed to the operating system for writing; it does not guarantee that
     * they are actually written to a physical device such as a disk drive.
     * <p>
     * The <code>flush</code> method of <code>OutputStream</code> does nothing.
     *
     * @exception  IOException  if an I/O error occurs.
     */
    public void flush() throws IOException {
    }

    /**
     * Closes this output stream and releases any system resources 
     * associated with this stream. The general contract of <code>close</code> 
     * is that it closes the output stream. A closed stream cannot perform 
     * output operations and cannot be reopened.
     * <p>
     * The <code>close</code> method of <code>OutputStream</code> does nothing.
     *
     * @exception  IOException  if an I/O error occurs.
     */
    public void close() throws IOException {
    }

}