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 }