001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.output;
018
019import java.io.IOException;
020import java.io.Writer;
021
022/**
023 * Throws an IOException on all attempts to write with {@link #close()} implemented as a noop.
024 * <p>
025 * Typically uses of this class include testing for corner cases in methods that accept a writer and acting as a
026 * sentinel value instead of a {@code null} writer.
027 * </p>
028 *
029 * @since 2.7
030 */
031public class ClosedWriter extends Writer {
032
033    /**
034     * The singleton instance.
035     *
036     * @since 2.12.0
037     */
038    public static final ClosedWriter INSTANCE = new ClosedWriter();
039
040    /**
041     * The singleton instance.
042     *
043     * @deprecated Use {@link #INSTANCE}.
044     */
045    @Deprecated
046    public static final ClosedWriter CLOSED_WRITER = INSTANCE;
047
048    /**
049     * Construct a new instance.
050     */
051    public ClosedWriter() {
052        // empty
053    }
054
055    @Override
056    public void close() throws IOException {
057        // noop
058    }
059
060    /**
061     * Throws an {@link IOException} to indicate that the stream is closed.
062     *
063     * @throws IOException always thrown
064     */
065    @Override
066    public void flush() throws IOException {
067        throw new IOException("flush() failed: stream is closed");
068    }
069
070    /**
071     * Throws an {@link IOException} to indicate that the writer is closed.
072     *
073     * @param cbuf ignored
074     * @param off ignored
075     * @param len ignored
076     * @throws IOException always thrown
077     */
078    @Override
079    public void write(final char[] cbuf, final int off, final int len) throws IOException {
080        throw new IOException("write(" + new String(cbuf) + ", " + off + ", " + len + ") failed: stream is closed");
081    }
082}