    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     */
    017    package org.apache.commons.io.filefilter;
    018
    019    import java.io.File;
    020    import java.io.Serializable;
    021
    022    /**
    023     * This filter accepts <code>File</code>s that can be read.
    024     * <p>
    025     * Example, showing how to print out a list of the
    026     * current directory's <i>readable</i> files:
    027     *
    028     * <pre>
    029     * File dir = new File(".");
    030     * String[] files = dir.list( CanReadFileFilter.CAN_READ );
    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>un-readable</i> files:
    039     *
    040     * <pre>
    041     * File dir = new File(".");
    042     * String[] files = dir.list( CanReadFileFilter.CANNOT_READ );
    043     * for ( int i = 0; i &lt; files.length; i++ ) {
    044     *     System.out.println(files[i]);
    045     * }
    046     * </pre>
    047     *
    048     * <p>
    049     * Example, showing how to print out a list of the
    050     * current directory's <i>read-only</i> files:
    051     *
    052     * <pre>
    053     * File dir = new File(".");
    054     * String[] files = dir.list( CanReadFileFilter.READ_ONLY );
    055     * for ( int i = 0; i &lt; files.length; i++ ) {
    056     *     System.out.println(files[i]);
    057     * }
    058     * </pre>
    059     *
    060     * @since Commons IO 1.3
    061     * @version $Revision: 659817 $
    062     */
    063    public class CanReadFileFilter extends AbstractFileFilter implements Serializable {
    064
    065        /** Singleton instance of <i>readable</i> filter */
    066        public static final IOFileFilter CAN_READ = new CanReadFileFilter();
    067
    068        /** Singleton instance of not <i>readable</i> filter */
    069        public static final IOFileFilter CANNOT_READ = new NotFileFilter(CAN_READ);
    070
    071        /** Singleton instance of <i>read-only</i> filter */
    072        public static final IOFileFilter READ_ONLY = new AndFileFilter(CAN_READ,
    073                                                    CanWriteFileFilter.CANNOT_WRITE);
    074
    075        /**
    076         * Restrictive consructor.
    077         */
    078        protected CanReadFileFilter() {
    079        }
    080
    081        /**
    082         * Checks to see if the file can be read.
    083         *
    084         * @param file  the File to check.
    085         * @return <code>true</code> if the file can be
    086         *  read, otherwise <code>false</code>.
    087         */
    088        @Override
    089        public boolean accept(File file) {
    090            return file.canRead();
    091        }
    092
    093    }