    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
    023/**
    024 * Closed input stream. This stream returns EOF to all attempts to read
    025 * something from the stream.
    026 * <p>
    027 * Typically uses of this class include testing for corner cases in methods
    028 * that accept input streams and acting as a sentinel value instead of a
    029 * {@code null} input stream.
    030 * </p>
    031 *
    032 * @since 1.4
    033 */
    034public class ClosedInputStream extends InputStream {
    035
    036    /**
    037     * A singleton.
    038     */
    039    public static final ClosedInputStream CLOSED_INPUT_STREAM = new ClosedInputStream();
    040
    041    /**
    042     * Returns -1 to indicate that the stream is closed.
    043     *
    044     * @return always -1
    045     */
    046    @Override
    047    public int read() {
    048        return EOF;
    049    }
    050
    051}