SizeFileFilter.java revision 8978aac1977408b05e386ae846c30920c7faa0a6 
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 */
17package org.apache.commons.io.filefilter;
18
19import java.io.File;
20import 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 */
41public 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