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.Writer;
20
21 import org.apache.commons.io.IOUtils;
22
23 /**
24 * Never writes data. Calls never go beyond this class.
25 * <p>
26 * This {@link Writer} has no destination (file/socket etc.) and all characters written to it are ignored and lost.
27 * </p>
28 */
29 public class NullWriter extends Writer {
30
31 /**
32 * The singleton instance.
33 *
34 * @since 2.12.0
35 */
36 public static final NullWriter INSTANCE = new NullWriter();
37
38 /**
39 * The singleton instance.
40 *
41 * @deprecated Use {@link #INSTANCE}.
42 */
43 @Deprecated
44 public static final NullWriter NULL_WRITER = INSTANCE;
45
46 /**
47 * Constructs a new NullWriter.
48 *
49 * @deprecated Use {@link #INSTANCE}.
50 */
51 @Deprecated
52 public NullWriter() {
53 }
54
55 /**
56 * Does nothing, like writing to {@code /dev/null}.
57 *
58 * @param c The character to write.
59 * @return this writer.
60 * @since 2.0
61 */
62 @Override
63 public Writer append(final char c) {
64 //to /dev/null
65 return this;
66 }
67
68 /**
69 * Does nothing, like writing to {@code /dev/null}.
70 *
71 * @param csq The character sequence to write.
72 * @return this writer
73 * @since 2.0
74 */
75 @Override
76 public Writer append(final CharSequence csq) {
77 //to /dev/null
78 return this;
79 }
80
81 /**
82 * Does nothing except argument validation, like writing to {@code /dev/null}.
83 *
84 * @param csq The character sequence from which a subsequence will be
85 * appended.
86 * If {@code csq} is {@code null}, it is treated as if it were
87 * {@code "null"}.
88 * @param start The index of the first character in the subsequence.
89 * @param end The index of the character following the last character in the
90 * subsequence.
91 * @return {@code this} instance.
92 * @throws IndexOutOfBoundsException If {@code start} or {@code end} are negative, {@code end} is
93 * greater than {@code csq.length()}, or {@code start} is greater
94 * than {@code end}.
95 * @since 2.0
96 */
97 @Override
98 public Writer append(final CharSequence csq, final int start, final int end) {
99 IOUtils.checkFromToIndex(csq, start, end);
100 //to /dev/null
101 return this;
102 }
103
104 /** @see Writer#close() */
105 @Override
106 public void close() {
107 //to /dev/null
108 }
109
110 /** @see Writer#flush() */
111 @Override
112 public void flush() {
113 //to /dev/null
114 }
115
116 /**
117 * Does nothing except argument validation, like writing to {@code /dev/null}.
118 *
119 * @param chr The characters to write, not {@code null}.
120 * @throws NullPointerException if {@code chr} is {@code null}.
121 */
122 @Override
123 public void write(final char[] chr) {
124 write(chr, 0, chr.length);
125 //to /dev/null
126 }
127
128 /**
129 * Does nothing except argument validation, like writing to {@code /dev/null}.
130 *
131 * @param cbuf The characters to write, not {@code null}.
132 * @param off The start offset.
133 * @param len The number of characters to write.
134 * @throws NullPointerException if {@code chr} is {@code null}.
135 * @throws IndexOutOfBoundsException If ({@code off} or {@code len} are negative, or {@code off + len} is greater than {@code cbuf.length}.
136 */
137 @Override
138 public void write(final char[] cbuf, final int off, final int len) {
139 IOUtils.checkFromIndexSize(cbuf, off, len);
140 //to /dev/null
141 }
142
143 /**
144 * Does nothing, like writing to {@code /dev/null}.
145 *
146 * @param b The character to write.
147 */
148 @Override
149 public void write(final int b) {
150 //to /dev/null
151 }
152
153 /**
154 * Does nothing except argument validation, like writing to {@code /dev/null}.
155 *
156 * @param str The string to write, not {@code null}.
157 * @throws NullPointerException if {@code str} is {@code null}.
158 */
159 @Override
160 public void write(final String str) {
161 write(str, 0, str.length());
162 //to /dev/null
163 }
164
165 /**
166 * Does nothing except argument validation, like writing to {@code /dev/null}.
167 *
168 * @param str The string to write, not {@code null}.
169 * @param off The start offset.
170 * @param len The number of characters to write.
171 * @throws NullPointerException If {@code str} is {@code null}.
172 * @throws IndexOutOfBoundsException If ({@code off} or {@code len} are negative, or {@code off + len} is greater than {@code str.length()}.
173 */
174 @Override
175 public void write(final String str, final int off, final int len) {
176 IOUtils.checkFromIndexSize(str, off, len);
177 //to /dev/null
178 }
179
180 }