    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</code> input stream.
    028     *
    029     * @version $Id: ClosedInputStream.java 659817 2008-05-24 13:23:10Z niallp $
    030     * @since Commons IO 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    }