1/*
2 * Copyright (C) 2006 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.io;
18
19import com.google.common.annotations.Beta;
20import com.google.common.base.Preconditions;
21
22import java.io.File;
23import java.io.FilenameFilter;
24import java.util.regex.Pattern;
25import java.util.regex.PatternSyntaxException;
26
27import javax.annotation.Nullable;
28
29/**
30 * File name filter that only accepts files matching a regular expression. This class is thread-safe
31 * and immutable.
32 *
33 * @author Apple Chow
34 * @since 1.0
35 */
36@Beta
37public final class PatternFilenameFilter implements FilenameFilter {
38
39  private final Pattern pattern;
40
41  /**
42   * Constructs a pattern file name filter object.
43   * @param patternStr the pattern string on which to filter file names
44   *
45   * @throws PatternSyntaxException if pattern compilation fails (runtime)
46   */
47  public PatternFilenameFilter(String patternStr) {
48    this(Pattern.compile(patternStr));
49  }
50
51  /**
52   * Constructs a pattern file name filter object.
53   * @param pattern the pattern on which to filter file names
54   */
55  public PatternFilenameFilter(Pattern pattern) {
56    this.pattern = Preconditions.checkNotNull(pattern);
57  }
58
59  @Override public boolean accept(@Nullable File dir, String fileName) {
60    return pattern.matcher(fileName).matches();
61  }
62}
63