/*

 * Copyright (c) 1994, 2019, 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 {

    /**

     * Constructor for subclasses to call.

     */

    public OutputStream() {}

    /**

     * 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>.

     *             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.

     * @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.

     *             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.

     *

     */

    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.

     *

     */

    public void close() throws IOException {

    }

}