001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.output;
018
019import java.io.Writer;
020
021import org.apache.commons.io.IOUtils;
022
023/**
024 * Never writes data. Calls never go beyond this class.
025 * <p>
026 * This {@link Writer} has no destination (file/socket etc.) and all characters written to it are ignored and lost.
027 * </p>
028 */
029public class NullWriter extends Writer {
030
031    /**
032     * The singleton instance.
033     *
034     * @since 2.12.0
035     */
036    public static final NullWriter INSTANCE = new NullWriter();
037
038    /**
039     * The singleton instance.
040     *
041     * @deprecated Use {@link #INSTANCE}.
042     */
043    @Deprecated
044    public static final NullWriter NULL_WRITER = INSTANCE;
045
046    /**
047     * Constructs a new NullWriter.
048     *
049     * @deprecated Use {@link #INSTANCE}.
050     */
051    @Deprecated
052    public NullWriter() {
053    }
054
055    /**
056     * Does nothing, like writing to {@code /dev/null}.
057     *
058     * @param c The character to write.
059     * @return this writer.
060     * @since 2.0
061     */
062    @Override
063    public Writer append(final char c) {
064        //to /dev/null
065        return this;
066    }
067
068    /**
069     * Does nothing, like writing to {@code /dev/null}.
070     *
071     * @param csq The character sequence to write.
072     * @return this writer
073     * @since 2.0
074     */
075    @Override
076    public Writer append(final CharSequence csq) {
077        //to /dev/null
078        return this;
079    }
080
081    /**
082     * Does nothing except argument validation, like writing to {@code /dev/null}.
083     *
084     * @param csq   The character sequence from which a subsequence will be
085     *              appended.
086     *              If {@code csq} is {@code null}, it is treated as if it were
087     *              {@code "null"}.
088     * @param start The index of the first character in the subsequence.
089     * @param end   The index of the character following the last character in the
090     *              subsequence.
091     * @return {@code this} instance.
092     * @throws IndexOutOfBoundsException If {@code start} or {@code end} are negative, {@code end} is
093     *                                   greater than {@code csq.length()}, or {@code start} is greater
094     *                                   than {@code end}.
095     * @since 2.0
096     */
097    @Override
098    public Writer append(final CharSequence csq, final int start, final int end) {
099        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}