001/*
002 * Copyright (C) 2006 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.io;
018
019import com.google.common.annotations.Beta;
020import com.google.common.base.Preconditions;
021
022import java.io.File;
023import java.io.FilenameFilter;
024import java.util.regex.Pattern;
025import java.util.regex.PatternSyntaxException;
026
027/**
028 * File name filter that only accepts files matching a regular expression.
029 *
030 * @author Apple Chow
031 * @since 1
032 */
033@Beta
034public final class PatternFilenameFilter implements FilenameFilter {
035
036  private final Pattern pattern;
037
038  /**
039   * Constructs a pattern file name filter object.
040   * @param patternStr the pattern string on which to filter file names
041   *
042   * @throws PatternSyntaxException if pattern compilation fails (runtime)
043   */
044  public PatternFilenameFilter(String patternStr) {
045    this(Pattern.compile(patternStr));
046  }
047
048  /**
049   * Constructs a pattern file name filter object.
050   * @param pattern the pattern on which to filter file names
051   */
052  public PatternFilenameFilter(Pattern pattern) {
053    this.pattern = Preconditions.checkNotNull(pattern);
054  }
055
056  @Override public boolean accept(File dir, String fileName) {
057    return pattern.matcher(fileName).matches();
058  }
059}