    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.comparator;
    018
    019import java.io.File;
    020import java.io.Serializable;
    021import java.util.Comparator;
    022
    023import org.apache.commons.io.IOCase;
    024
    025/**
    026 * Compare the <strong>names</strong> of two files for order (see {@link File#getName()}).
    027 * <p>
    028 * This comparator can be used to sort lists or arrays of files
    029 * by their name either in a case-sensitive, case-insensitive or
    030 * system dependent case-sensitive way. A number of singleton instances
    031 * are provided for the various case sensitivity options (using {@link IOCase})
    032 * and the reverse of those options.
    033 * </p>
    034 * <p>
    035 * Example of a <em>case-sensitive</em> file name sort using the
    036 * {@link #NAME_COMPARATOR} singleton instance:
    037 * </p>
    038 * <pre>
    039 *       List&lt;File&gt; list = ...
    040 *       ((AbstractFileComparator) NameFileComparator.NAME_COMPARATOR).sort(list);
    041 * </pre>
    042 * <p>
    043 * Example of a <em>reverse case-insensitive</em> file name sort using the
    044 * {@link #NAME_INSENSITIVE_REVERSE} singleton instance:
    045 * </p>
    046 * <pre>
    047 *       File[] array = ...
    048 *       ((AbstractFileComparator) NameFileComparator.NAME_INSENSITIVE_REVERSE).sort(array);
    049 * </pre>
    050 * <h2>Deprecating Serialization</h2>
    051 * <p>
    052 * <em>Serialization is deprecated and will be removed in 3.0.</em>
    053 * </p>
    054 *
    055 * @since 1.4
    056 */
    057public class NameFileComparator extends AbstractFileComparator implements Serializable {
    058
    059    private static final long serialVersionUID = 8397947749814525798L;
    060
    061    /** Case-sensitive name comparator instance (see {@link IOCase#SENSITIVE}) */
    062    public static final Comparator<File> NAME_COMPARATOR = new NameFileComparator();
    063
    064    /** Reverse case-sensitive name comparator instance (see {@link IOCase#SENSITIVE}) */
    065    public static final Comparator<File> NAME_REVERSE = new ReverseFileComparator(NAME_COMPARATOR);
    066
    067    /** Case-insensitive name comparator instance (see {@link IOCase#INSENSITIVE}) */
    068    public static final Comparator<File> NAME_INSENSITIVE_COMPARATOR = new NameFileComparator(IOCase.INSENSITIVE);
    069
    070    /** Reverse case-insensitive name comparator instance (see {@link IOCase#INSENSITIVE}) */
    071    public static final Comparator<File> NAME_INSENSITIVE_REVERSE = new ReverseFileComparator(NAME_INSENSITIVE_COMPARATOR);
    072
    073    /** System sensitive name comparator instance (see {@link IOCase#SYSTEM}) */
    074    public static final Comparator<File> NAME_SYSTEM_COMPARATOR = new NameFileComparator(IOCase.SYSTEM);
    075
    076    /** Reverse system sensitive name comparator instance (see {@link IOCase#SYSTEM}) */
    077    public static final Comparator<File> NAME_SYSTEM_REVERSE = new ReverseFileComparator(NAME_SYSTEM_COMPARATOR);
    078
    079    /** Whether the comparison is case-sensitive. */
    080    private final IOCase ioCase;
    081
    082    /**
    083     * Constructs a case-sensitive file name comparator instance.
    084     */
    085    public NameFileComparator() {
    086        this.ioCase = IOCase.SENSITIVE;
    087    }
    088
    089    /**
    090     * Constructs a file name comparator instance with the specified case-sensitivity.
    091     *
    092     * @param ioCase  how to handle case sensitivity, null means case-sensitive
    093     */
    094    public NameFileComparator(final IOCase ioCase) {
    095        this.ioCase = IOCase.value(ioCase, IOCase.SENSITIVE);
    096    }
    097
    098    /**
    099     * Compares the names of two files with the specified case sensitivity.
    100     *
    101     * @param file1 The first file to compare
    102     * @param file2 The second file to compare
    103     * @return a negative value if the first file's name
    104     * is less than the second, zero if the names are the
    105     * same and a positive value if the first files name
    106     * is greater than the second file.
    107     */
    108    @Override
    109    public int compare(final File file1, final File file2) {
    110        return ioCase.checkCompareTo(file1.getName(), file2.getName());
    111    }
    112
    113    /**
    114     * String representation of this file comparator.
    115     *
    116     * @return String representation of this file comparator
    117     */
    118    @Override
    119    public String toString() {
    120        return super.toString() + "[ioCase=" + ioCase + "]";
    121    }
    122}