1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.io.filefilter; 18 19 import java.io.File; 20 21 /** 22 * This filter accepts files or directories that are empty. 23 * <p> 24 * If the <code>File</code> is a directory it checks that 25 * it contains no files. 26 * <p> 27 * Example, showing how to print out a list of the 28 * current directory's empty files/directories: 29 * 30 * <pre> 31 * File dir = new File("."); 32 * String[] files = dir.list( EmptyFileFilter.EMPTY ); 33 * for ( int i = 0; i < files.length; i++ ) { 34 * System.out.println(files[i]); 35 * } 36 * </pre> 37 * 38 * <p> 39 * Example, showing how to print out a list of the 40 * current directory's non-empty files/directories: 41 * 42 * <pre> 43 * File dir = new File("."); 44 * String[] files = dir.list( EmptyFileFilter.NOT_EMPTY ); 45 * for ( int i = 0; i < files.length; i++ ) { 46 * System.out.println(files[i]); 47 * } 48 * </pre> 49 * 50 * @since Commons IO 1.3 51 * @version $Revision: 437567 $ 52 */ 53 public class EmptyFileFilter extends AbstractFileFilter { 54 55 /** Singleton instance of <i>empty</i> filter */ 56 public static final IOFileFilter EMPTY = new EmptyFileFilter(); 57 58 /** Singleton instance of <i>not-empty</i> filter */ 59 public static final IOFileFilter NOT_EMPTY = new NotFileFilter(EMPTY); 60 61 /** 62 * Restrictive consructor. 63 */ 64 protected EmptyFileFilter() { 65 } 66 67 /** 68 * Checks to see if the file is empty. 69 * 70 * @param file the file or directory to check 71 * @return <code>true</code> if the file or directory 72 * is <i>empty</i>, otherwise <code>false</code>. 73 */ 74 public boolean accept(File file) { 75 if (file.isDirectory()) { 76 File[] files = file.listFiles(); 77 return (files == null || files.length == 0); 78 } else { 79 return (file.length() == 0); 80 } 81 } 82 83 }