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; 021import java.nio.file.FileVisitResult; 022import java.nio.file.Files; 023import java.nio.file.Path; 024import java.nio.file.attribute.BasicFileAttributes; 025 026/** 027 * This filter accepts {@link File}s that are directories. 028 * <p> 029 * For example, here is how to print out a list of the current directory's subdirectories: 030 * </p> 031 * <h2>Using Classic IO</h2> 032 * 033 * <pre> 034 * File dir = FileUtils.current(); 035 * String[] files = dir.list(DirectoryFileFilter.INSTANCE); 036 * for (String file : files) { 037 * System.out.println(file); 038 * } 039 * </pre> 040 * 041 * <h2>Using NIO</h2> 042 * 043 * <pre> 044 * final Path dir = PathUtils.current(); 045 * final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(DirectoryFileFilter.INSTANCE); 046 * // 047 * // Walk one dir 048 * Files.<b>walkFileTree</b>(dir, Collections.emptySet(), 1, visitor); 049 * System.out.println(visitor.getPathCounters()); 050 * System.out.println(visitor.getFileList()); 051 * // 052 * visitor.getPathCounters().reset(); 053 * // 054 * // Walk dir tree 055 * Files.<b>walkFileTree</b>(dir, visitor); 056 * System.out.println(visitor.getPathCounters()); 057 * System.out.println(visitor.getDirList()); 058 * System.out.println(visitor.getFileList()); 059 * </pre> 060 * <h2>Deprecating Serialization</h2> 061 * <p> 062 * <em>Serialization is deprecated and will be removed in 3.0.</em> 063 * </p> 064 * 065 * @since 1.0 066 * @see FileFilterUtils#directoryFileFilter() 067 */ 068public class DirectoryFileFilter extends AbstractFileFilter implements Serializable { 069 070 /** 071 * Singleton instance of directory filter. 072 * 073 * @since 1.3 074 */ 075 public static final IOFileFilter DIRECTORY = new DirectoryFileFilter(); 076 077 /** 078 * Singleton instance of directory filter. Please use the identical DirectoryFileFilter.DIRECTORY constant. The new 079 * name is more JDK 1.5 friendly as it doesn't clash with other values when using static imports. 080 */ 081 public static final IOFileFilter INSTANCE = DIRECTORY; 082 083 private static final long serialVersionUID = -5148237843784525732L; 084 085 /** 086 * Restrictive constructor. 087 */ 088 protected DirectoryFileFilter() { 089 // empty. 090 } 091 092 /** 093 * Checks to see if the file is a directory. 094 * 095 * @param file the File to check 096 * @return true if the file is a directory 097 */ 098 @Override 099 public boolean accept(final File file) { 100 return file != null && file.isDirectory(); 101 } 102 103 /** 104 * Checks to see if the file is a directory. 105 * @param file the File to check 106 * 107 * @return true if the file is a directory 108 * @since 2.9.0 109 */ 110 @Override 111 public FileVisitResult accept(final Path file, final BasicFileAttributes attributes) { 112 return toFileVisitResult(file != null && Files.isDirectory(file)); 113 } 114 115}