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 * https://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
18 package org.apache.commons.io.output;
19
20 import java.io.IOException;
21 import java.io.Writer;
22 import java.util.Arrays;
23
24 /**
25 * Throws an IOException on all attempts to write with {@link #close()} implemented as a noop.
26 * <p>
27 * Typically uses of this class include testing for corner cases in methods that accept a writer and acting as a sentinel value instead of a {@code null}
28 * writer.
29 * </p>
30 *
31 * @since 2.7
32 */
33 public class ClosedWriter extends Writer {
34
35 /**
36 * The singleton instance.
37 *
38 * @since 2.12.0
39 */
40 public static final ClosedWriter INSTANCE = new ClosedWriter();
41
42 /**
43 * The singleton instance.
44 *
45 * @deprecated Use {@link #INSTANCE}.
46 */
47 @Deprecated
48 public static final ClosedWriter CLOSED_WRITER = INSTANCE;
49
50 /**
51 * Construct a new instance.
52 */
53 public ClosedWriter() {
54 // empty
55 }
56
57 @Override
58 public void close() throws IOException {
59 // noop
60 }
61
62 /**
63 * Throws an {@link IOException} to indicate that the stream is closed.
64 *
65 * @throws IOException always thrown.
66 */
67 @Override
68 public void flush() throws IOException {
69 throw new IOException("flush() failed: stream is closed");
70 }
71
72 /**
73 * Throws an {@link IOException} to indicate that the writer is closed.
74 *
75 * @param cbuf ignored.
76 * @param off ignored.
77 * @param len ignored.
78 * @throws IOException always thrown.
79 */
80 @Override
81 public void write(final char[] cbuf, final int off, final int len) throws IOException {
82 throw new IOException(String.format("write(%s, %d, %d) failed: stream is closed", Arrays.toString(cbuf), off, len));
83 }
84 }