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 *      http://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.filefilter;
018
019import java.io.File;
020import java.io.IOException;
021import java.io.Serializable;
022import java.nio.file.FileVisitResult;
023import java.nio.file.Files;
024import java.nio.file.Path;
025import java.nio.file.attribute.BasicFileAttributes;
026
027/**
028 * This filter accepts {@code File}s that are hidden.
029 * <p>
030 * Example, showing how to print out a list of the
031 * current directory's <i>hidden</i> files:
032 * </p>
033 * <h2>Using Classic IO</h2>
034 * <pre>
035 * File dir = new File(".");
036 * String[] files = dir.list(HiddenFileFilter.HIDDEN);
037 * for (String file : files) {
038 *     System.out.println(file);
039 * }
040 * </pre>
041 *
042 * <p>
043 * Example, showing how to print out a list of the
044 * current directory's <i>visible</i> (i.e. not hidden) files:
045 * </p>
046 *
047 * <pre>
048 * File dir = new File(".");
049 * String[] files = dir.list(HiddenFileFilter.VISIBLE);
050 * for (String file : files) {
051 *     System.out.println(file);
052 * }
053 * </pre>
054 *
055 * <h2>Using NIO</h2>
056 * <pre>
057 * final Path dir = Paths.get("");
058 * final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(HiddenFileFilter.HIDDEN);
059 * //
060 * // Walk one dir
061 * Files.<b>walkFileTree</b>(dir, Collections.emptySet(), 1, visitor);
062 * System.out.println(visitor.getPathCounters());
063 * System.out.println(visitor.getFileList());
064 * //
065 * visitor.getPathCounters().reset();
066 * //
067 * // Walk dir tree
068 * Files.<b>walkFileTree</b>(dir, visitor);
069 * System.out.println(visitor.getPathCounters());
070 * System.out.println(visitor.getDirList());
071 * System.out.println(visitor.getFileList());
072 * </pre>
073 *
074 * @since 1.3
075 */
076public class HiddenFileFilter extends AbstractFileFilter implements Serializable {
077
078    /** Singleton instance of <i>hidden</i> filter */
079    public static final IOFileFilter HIDDEN  = new HiddenFileFilter();
080
081    private static final long serialVersionUID = 8930842316112759062L;
082
083    /** Singleton instance of <i>visible</i> filter */
084    public static final IOFileFilter VISIBLE = HIDDEN.negate();
085
086    /**
087     * Restrictive constructor.
088     */
089    protected HiddenFileFilter() {
090    }
091
092    /**
093     * Checks to see if the file is hidden.
094     *
095     * @param file  the File to check
096     * @return {@code true} if the file is
097     *  <i>hidden</i>, otherwise {@code false}.
098     */
099    @Override
100    public boolean accept(final File file) {
101        return file.isHidden();
102    }
103
104    /**
105     * Checks to see if the file is hidden.
106     * @param file  the File to check
107     *
108     * @return {@code true} if the file is
109     *  <i>hidden</i>, otherwise {@code false}.
110     * @since 2.9.0
111     */
112    @Override
113    public FileVisitResult accept(final Path file, final BasicFileAttributes attributes) {
114        try {
115            return toFileVisitResult(Files.isHidden(file), file);
116        } catch (final IOException e) {
117            return handle(e);
118        }
119    }
120
121}