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 < 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 < 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 < 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 }