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.input;
018
019import static org.apache.commons.io.IOUtils.EOF;
020
021import java.io.InputStream;
022
023import org.apache.commons.io.IOUtils;
024
025/**
026 * Always returns {@link IOUtils#EOF} to all attempts to read something from the stream.
027 * <p>
028 * Typically uses of this class include testing for corner cases in methods that accept input streams and acting as a
029 * sentinel value instead of a {@code null} input stream.
030 * </p>
031 *
032 * @since 1.4
033 */
034public class ClosedInputStream extends InputStream {
035
036    /**
037     * The singleton instance.
038     *
039     * @since 2.12.0
040     */
041    public static final ClosedInputStream INSTANCE = new ClosedInputStream();
042
043    /**
044     * The singleton instance.
045     *
046     * @deprecated Use {@link #INSTANCE}.
047     */
048    @Deprecated
049    public static final ClosedInputStream CLOSED_INPUT_STREAM = INSTANCE;
050
051    /**
052     * Returns -1 to indicate that the stream is closed.
053     *
054     * @return always -1
055     */
056    @Override
057    public int read() {
058        return EOF;
059    }
060
061}