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