001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache license, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the license for the specific language governing permissions and 015 * limitations under the license. 016 */ 017package org.apache.logging.log4j.core.util; 018 019import java.util.HashSet; 020import java.util.Set; 021 022/** 023 * Set-related convenience methods. 024 */ 025public final class SetUtils { 026 private SetUtils() { 027 } 028 029 /** 030 * Extracts the Strings from a Set that start with a given prefix. 031 * 032 * @param set a Set of Strings (assumed to all be non-{@code null}) 033 * @param prefix the prefix to look for in the string set 034 * @return an array of the matching strings from the given set 035 */ 036 public static String[] prefixSet(final Set<String> set, final String prefix) { 037 final Set<String> prefixSet = new HashSet<>(); 038 for (final String str : set) { 039 if (str.startsWith(prefix)) { 040 prefixSet.add(str); 041 } 042 } 043 return prefixSet.toArray(new String[prefixSet.size()]); 044 } 045}