    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}