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
22 import org.apache.commons.io.IOUtils;
23
24 /**
25 * Appends all data to the famous <strong>/dev/null</strong>.
26 * <p>
27 * This Appendable has no destination (file/socket etc.) and all characters written to it are ignored and lost.
28 * </p>
29 *
30 * @since 2.8.0
31 */
32 public class NullAppendable implements Appendable { // NOPMD Class will be final in 3.0.
33
34 /**
35 * A singleton.
36 */
37 public static final NullAppendable INSTANCE = new NullAppendable();
38
39 /** Use the singleton. */
40 private NullAppendable() {
41 // no instances.
42 }
43
44 @Override
45 public Appendable append(final char c) throws IOException {
46 return this;
47 }
48
49 @Override
50 public Appendable append(final CharSequence csq) throws IOException {
51 return this;
52 }
53
54 /**
55 * Does nothing except argument validation, like writing to {@code /dev/null}.
56 *
57 * @param csq The character sequence from which a subsequence will be
58 * appended.
59 * If {@code csq} is {@code null}, it is treated as if it were
60 * {@code "null"}.
61 * @param start The index of the first character in the subsequence.
62 * @param end The index of the character following the last character in the
63 * subsequence.
64 * @return {@code this} instance.
65 * @throws IndexOutOfBoundsException If {@code start} or {@code end} are negative, {@code end} is
66 * greater than {@code csq.length()}, or {@code start} is greater
67 * than {@code end}.
68 */
69 @Override
70 public Appendable append(final CharSequence csq, final int start, final int end) throws IOException {
71 IOUtils.checkFromToIndex(csq, start, end);
72 return this;
73 }
74
75 }