1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.io.input;
18
19 import static org.apache.commons.io.IOUtils.EOF;
20
21 import java.io.IOException;
22 import java.io.Reader;
23
24 import org.apache.commons.io.IOUtils;
25
26 /**
27 * Always returns {@link IOUtils#EOF} to all attempts to read something from it.
28 * <p>
29 * Typically uses of this class include testing for corner cases in methods that accept readers and acting as a sentinel
30 * value instead of a {@code null} reader.
31 * </p>
32 *
33 * @since 2.7
34 */
35 public class ClosedReader extends Reader {
36
37 /**
38 * The singleton instance.
39 *
40 * @since 2.12.0
41 */
42 public static final ClosedReader INSTANCE = new ClosedReader();
43
44 /**
45 * The singleton instance.
46 *
47 * @deprecated {@link #INSTANCE}.
48 */
49 @Deprecated
50 public static final ClosedReader CLOSED_READER = INSTANCE;
51
52 @Override
53 public void close() throws IOException {
54 // noop
55 }
56
57 /**
58 * Returns -1 to indicate that the stream is closed.
59 *
60 * @param cbuf ignored
61 * @param off ignored
62 * @param len ignored
63 * @return always -1
64 */
65 @Override
66 public int read(final char[] cbuf, final int off, final int len) {
67 return EOF;
68 }
69
70 }