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 directories. 024 * <p> 025 * For example, here is how to print out a list of the 026 * current directory's subdirectories: 027 * 028 * <pre> 029 * File dir = new File("."); 030 * String[] files = dir.list( DirectoryFileFilter.INSTANCE ); 031 * for ( int i = 0; i < files.length; i++ ) { 032 * System.out.println(files[i]); 033 * } 034 * </pre> 035 * 036 * @since 1.0 037 * @version $Id: DirectoryFileFilter.java 1642757 2014-12-01 21:09:30Z sebb $ 038 * 039 * @see FileFilterUtils#directoryFileFilter() 040 */ 041public class DirectoryFileFilter extends AbstractFileFilter implements Serializable { 042 043 private static final long serialVersionUID = -5148237843784525732L; 044 /** 045 * Singleton instance of directory filter. 046 * @since 1.3 047 */ 048 public static final IOFileFilter DIRECTORY = new DirectoryFileFilter(); 049 /** 050 * Singleton instance of directory filter. 051 * Please use the identical DirectoryFileFilter.DIRECTORY constant. 052 * The new name is more JDK 1.5 friendly as it doesn't clash with other 053 * values when using static imports. 054 */ 055 public static final IOFileFilter INSTANCE = DIRECTORY; 056 057 /** 058 * Restrictive consructor. 059 */ 060 protected DirectoryFileFilter() { 061 } 062 063 /** 064 * Checks to see if the file is a directory. 065 * 066 * @param file the File to check 067 * @return true if the file is a directory 068 */ 069 @Override 070 public boolean accept(final File file) { 071 return file.isDirectory(); 072 } 073 074}