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.InputStream;
23
24 import org.apache.commons.io.IOUtils;
25
26 /**
27 * Always returns {@link IOUtils#EOF} to all attempts to read something from an input stream.
28 * <p>
29 * Typically uses of this class include testing for corner cases in methods that accept input streams and acting as a
30 * sentinel value instead of a {@code null} input stream.
31 * </p>
32 *
33 * @since 1.4
34 */
35 public class ClosedInputStream extends InputStream {
36
37 /**
38 * The singleton instance.
39 *
40 * @since 2.12.0
41 */
42 public static final ClosedInputStream INSTANCE = new ClosedInputStream();
43
44 /**
45 * The singleton instance.
46 *
47 * @deprecated Use {@link #INSTANCE}.
48 */
49 @Deprecated
50 public static final ClosedInputStream CLOSED_INPUT_STREAM = INSTANCE;
51
52 /**
53 * Returns {@link #INSTANCE} if the given InputStream is null, otherwise returns the given input stream.
54 *
55 * @param in the InputStream to test.
56 * @return {@link #INSTANCE} if the given InputStream is null, otherwise returns the given input stream.
57 */
58 static InputStream ifNull(final InputStream in) {
59 return in != null ? in : INSTANCE;
60 }
61
62 /**
63 * Construct a new instance.
64 */
65 public ClosedInputStream() {
66 // empty
67 }
68
69 /**
70 * Returns -1 to indicate that the stream is closed.
71 *
72 * @return always -1
73 */
74 @Override
75 public int read() {
76 return EOF;
77 }
78
79 /**
80 * Returns -1 to indicate that the stream is closed.
81 *
82 * @param b ignored.
83 * @param off ignored.
84 * @param len ignored.
85 * @return always -1
86 */
87 @Override
88 public int read(final byte[] b, final int off, final int len) throws IOException {
89 return EOF;
90 }
91
92 }