    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.Serializable;
    021
    022/**
    023 * This filter accepts <code>File</code>s that are hidden.
    024 * <p>
    025 * Example, showing how to print out a list of the
    026 * current directory's <i>hidden</i> files:
    027 *
    028 * <pre>
    029 * File dir = new File(".");
    030 * String[] files = dir.list( HiddenFileFilter.HIDDEN );
    031 * for ( int i = 0; i &lt; files.length; i++ ) {
    032 *     System.out.println(files[i]);
    033 * }
    034 * </pre>
    035 *
    036 * <p>
    037 * Example, showing how to print out a list of the
    038 * current directory's <i>visible</i> (i.e. not hidden) files:
    039 *
    040 * <pre>
    041 * File dir = new File(".");
    042 * String[] files = dir.list( HiddenFileFilter.VISIBLE );
    043 * for ( int i = 0; i &lt; files.length; i++ ) {
    044 *     System.out.println(files[i]);
    045 * }
    046 * </pre>
    047 *
    048 * @since 1.3
    049 *
    050 */
    051public class HiddenFileFilter extends AbstractFileFilter implements Serializable {
    052
    053    private static final long serialVersionUID = 8930842316112759062L;
    054
    055    /** Singleton instance of <i>hidden</i> filter */
    056    public static final IOFileFilter HIDDEN  = new HiddenFileFilter();
    057
    058    /** Singleton instance of <i>visible</i> filter */
    059    public static final IOFileFilter VISIBLE = new NotFileFilter(HIDDEN);
    060
    061    /**
    062     * Restrictive constructor.
    063     */
    064    protected HiddenFileFilter() {
    065    }
    066
    067    /**
    068     * Checks to see if the file is hidden.
    069     *
    070     * @param file  the File to check
    071     * @return {@code true} if the file is
    072     *  <i>hidden</i>, otherwise {@code false}.
    073     */
    074    @Override
    075    public boolean accept(final File file) {
    076        return file.isHidden();
    077    }
    078
    079}