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
027import javax.annotation.Nullable;
028
029/**
030 * File name filter that only accepts files matching a regular expression. This
031 * class is thread-safe and immutable.
032 *
033 * @author Apple Chow
034 * @since 1.0
035 */
036@Beta
037public final class PatternFilenameFilter implements FilenameFilter {
038
039  private final Pattern pattern;
040
041  /**
042   * Constructs a pattern file name filter object.
043   * @param patternStr the pattern string on which to filter file names
044   *
045   * @throws PatternSyntaxException if pattern compilation fails (runtime)
046   */
047  public PatternFilenameFilter(String patternStr) {
048    this(Pattern.compile(patternStr));
049  }
050
051  /**
052   * Constructs a pattern file name filter object.
053   * @param pattern the pattern on which to filter file names
054   */
055  public PatternFilenameFilter(Pattern pattern) {
056    this.pattern = Preconditions.checkNotNull(pattern);
057  }
058
059  @Override public boolean accept(@Nullable File dir, String fileName) {
060    return pattern.matcher(fileName).matches();
061  }
062}