    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.IOException;
    022import java.io.Reader;
    023
    024/**
    025 * Closed reader. This reader returns EOF to all attempts to read something from it.
    026 * <p>
    027 * Typically uses of this class include testing for corner cases in methods that accept readers and acting as a sentinel
    028 * value instead of a {@code null} reader.
    029 * </p>
    030 *
    031 * @since 2.7
    032 */
    033public class ClosedReader extends Reader {
    034
    035    /**
    036     * A singleton.
    037     */
    038    public static final ClosedReader CLOSED_READER = new ClosedReader();
    039
    040    /**
    041     * Returns -1 to indicate that the stream is closed.
    042     *
    043     * @param cbuf ignored
    044     * @param off  ignored
    045     * @param len  ignored
    046     * @return always -1
    047     */
    048    @Override
    049    public int read(final char[] cbuf, final int off, final int len) {
    050        return EOF;
    051    }
    052
    053    @Override
    054    public void close() throws IOException {
    055        // noop
    056    }
    057
    058}