Commons IO example source code file (EmptyFileFilter.java)

This example Commons IO source code file (EmptyFileFilter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons IO tags/keywords

abstractfilefilter, abstractfilefilter, empty, emptyfilefilter, emptyfilefilter, file, io, iofilefilter, iofilefilter, not_empty, notfilefilter, override, serializable, serializable

The Commons IO EmptyFileFilter.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.io.filefilter;

import java.io.File;
import java.io.Serializable;

/**
 * This filter accepts files or directories that are empty.
 * <p>
 * If the <code>File is a directory it checks that
 * it contains no files.
 * <p>
 * Example, showing how to print out a list of the 
 * current directory's empty files/directories:
 *
 * <pre>
 * File dir = new File(".");
 * String[] files = dir.list( EmptyFileFilter.EMPTY );
 * for ( int i = 0; i < files.length; i++ ) {
 *     System.out.println(files[i]);
 * }
 * </pre>
 *
 * <p>
 * Example, showing how to print out a list of the 
 * current directory's non-empty files/directories:
 *
 * <pre>
 * File dir = new File(".");
 * String[] files = dir.list( EmptyFileFilter.NOT_EMPTY );
 * for ( int i = 0; i < files.length; i++ ) {
 *     System.out.println(files[i]);
 * }
 * </pre>
 *
 * @since Commons IO 1.3
 * @version $Revision: 659817 $
 */
public class EmptyFileFilter extends AbstractFileFilter implements Serializable {
    
    /** Singleton instance of <i>empty filter */
    public static final IOFileFilter EMPTY = new EmptyFileFilter();
    
    /** Singleton instance of <i>not-empty filter */
    public static final IOFileFilter NOT_EMPTY = new NotFileFilter(EMPTY);
    
    /**
     * Restrictive consructor.
     */
    protected EmptyFileFilter() {
    }
    
    /**
     * Checks to see if the file is empty.
     * 
     * @param file  the file or directory to check
     * @return <code>true if the file or directory
     *  is <i>empty, otherwise false.
     */
    @Override
    public boolean accept(File file) {
        if (file.isDirectory()) {
            File[] files = file.listFiles();
            return (files == null || files.length == 0);
        } else {
            return (file.length() == 0);
        }
    }
    
}