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      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 import java.io.Serializable;
     21 
     22 /**
     23  * Filters files based on size, can filter either smaller files or
     24  * files equal to or larger than a given threshold.
     25  * <p>
     26  * For example, to print all files and directories in the
     27  * current directory whose size is greater than 1 MB:
     28  *
     29  * <pre>
     30  * File dir = new File(".");
     31  * String[] files = dir.list( new SizeFileFilter(1024 * 1024) );
     32  * for ( int i = 0; i &lt; files.length; i++ ) {
     33  *     System.out.println(files[i]);
     34  * }
     35  * </pre>
     36  *
     37  * @author Rahul Akolkar
     38  * @version $Id: SizeFileFilter.java 591058 2007-11-01 15:47:05Z niallp $
     39  * @since Commons IO 1.2
     40  */
     41 public class SizeFileFilter extends AbstractFileFilter implements Serializable {
     42 
     43     /** The size threshold. */
     44     private final long size;
     45     /** Whether the files accepted will be larger or smaller. */
     46     private final boolean acceptLarger;
     47 
     48     /**
     49      * Constructs a new size file filter for files equal to or
     50      * larger than a certain size.
     51      *
     52      * @param size  the threshold size of the files
     53      * @throws IllegalArgumentException if the size is negative
     54      */
     55     public SizeFileFilter(long size) {
     56         this(size, true);
     57     }
     58 
     59     /**
     60      * Constructs a new size file filter for files based on a certain size
     61      * threshold.
     62      *
     63      * @param size  the threshold size of the files
     64      * @param acceptLarger  if true, files equal to or larger are accepted,
     65      * otherwise smaller ones (but not equal to)
     66      * @throws IllegalArgumentException if the size is negative
     67      */
     68     public SizeFileFilter(long size, boolean acceptLarger) {
     69         if (size < 0) {
     70             throw new IllegalArgumentException("The size must be non-negative");
     71         }
     72         this.size = size;
     73         this.acceptLarger = acceptLarger;
     74     }
     75 
     76     //-----------------------------------------------------------------------
     77     /**
     78      * Checks to see if the size of the file is favorable.
     79      * <p>
     80      * If size equals threshold and smaller files are required,
     81      * file <b>IS NOT</b> selected.
     82      * If size equals threshold and larger files are required,
     83      * file <b>IS</b> selected.
     84      *
     85      * @param file  the File to check
     86      * @return true if the filename matches
     87      */
     88     public boolean accept(File file) {
     89         boolean smaller = file.length() < size;
     90         return acceptLarger ? !smaller : smaller;
     91     }
     92 
     93     /**
     94      * Provide a String representaion of this file filter.
     95      *
     96      * @return a String representaion
     97      */
     98     public String toString() {
     99         String condition = acceptLarger ? ">=" : "<";
    100         return super.toString() + "(" + condition + size + ")";
    101     }
    102 
    103 }
    104