/*
* 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</code> 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</i> filter */
public static final IOFileFilter EMPTY = new EmptyFileFilter();
/** Singleton instance of <i>not-empty</i> 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</code> if the file or directory
* is <i>empty</i>, otherwise <code>false</code>.
*/
@Override
public boolean accept(File file) {
if (file.isDirectory()) {
File[] files = file.listFiles();
return (files == null || files.length == 0);
} else {
return (file.length() == 0);
}
}
}
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