/*
 * Copyright (c) 1994, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation. Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package java.io;

import java.util.Objects;

/**
 * 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
 * @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 1.0
 */
public abstract class OutputStream implements Closeable, Flushable {
 /**
 * Returns a new {@code OutputStream} which discards all bytes. The
 * returned stream is initially open. The stream is closed by calling
 * the {@code close()} method. Subsequent calls to {@code close()} have
 * no effect.
 *
 * <p> While the stream is open, the {@code write(int)}, {@code
 * write(byte[])}, and {@code write(byte[], int, int)} methods do nothing.
 * After the stream has been closed, these methods all throw {@code
 * IOException}.
 *
 * <p> The {@code flush()} method does nothing.
 *
 * @return an {@code OutputStream} which discards all bytes
 *
 * @since 11
 */
 public static OutputStream nullOutputStream() {
 return new OutputStream() {
 private volatile boolean closed;

 private void ensureOpen() throws IOException {
 if (closed) {
 throw new IOException("Stream closed");
 }
 }

 @Override
 public void write(int b) throws IOException {
 ensureOpen();
 }

 @Override
 public void write(byte b[], int off, int len) throws IOException {
 Objects.checkFromIndexSize(off, len, b.length);
 ensureOpen();
 }

 @Override
 public void close() {
 closed = true;
 }
 };
 }

 /**
 * 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}, then an {@code IndexOutOfBoundsException} 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 {
 Objects.checkFromIndexSize(off, len, b.length);
 // len == 0 condition implicitly handled by loop bounds
 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 {
 }

}