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     */
017    package org.apache.commons.io.input;
018    
019    import java.io.InputStream;
020    
021    /**
022     * Closed input stream. This stream returns -1 to all attempts to read
023     * something from the stream.
024     * <p>
025     * Typically uses of this class include testing for corner cases in methods
026     * that accept input streams and acting as a sentinel value instead of a
027     * {@code null} input stream.
028     *
029     * @version $Id: ClosedInputStream.java 1307459 2012-03-30 15:11:44Z ggregory $
030     * @since 1.4
031     */
032    public class ClosedInputStream extends InputStream {
033        
034        /**
035         * A singleton.
036         */
037        public static final ClosedInputStream CLOSED_INPUT_STREAM = new ClosedInputStream();
038    
039        /**
040         * Returns -1 to indicate that the stream is closed.
041         *
042         * @return always -1
043         */
044        @Override
045        public int read() {
046            return -1;
047        }
048    
049    }