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 */
17 package org.apache.logging.log4j.core.util;
18
19 import java.util.HashSet;
20 import java.util.Set;
21
22 /**
23 *
24 *
25 *
26 */
27 public final class SetUtils {
28 private SetUtils() {}
29
30 /**
31 * Extracts the Strings from a Set that start with a given prefix.
32 *
33 * @param set a Set of Strings (assumed to all be non-{@code null})
34 * @param prefix the prefix to look for in the string set
35 * @return an array of the matching strings from the given set
36 */
37 public static String[] prefixSet(final Set<String> set, final String prefix) {
38 final Set<String> prefixSet = new HashSet<String>();
39 for (final String str : set) {
40 if (str.startsWith(prefix)) {
41 prefixSet.add(str);
42 }
43 }
44 return prefixSet.toArray(new String[prefixSet.size()]);
45 }
46 }