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
017 package com.google.common.io;
018
019 import com.google.common.annotations.Beta;
020 import com.google.common.base.Preconditions;
021
022 import java.io.File;
023 import java.io.FilenameFilter;
024 import java.util.regex.Pattern;
025 import java.util.regex.PatternSyntaxException;
026
027 import javax.annotation.Nullable;
028
029 /**
030 * File name filter that only accepts files matching a regular expression. This class is thread-safe
031 * and immutable.
032 *
033 * @author Apple Chow
034 * @since 1.0
035 */
036 @Beta
037 public 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 }