    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     */
    017    package org.apache.logging.log4j.core.util;
    018
    019    import java.util.HashSet;
    020    import java.util.Set;
    021
    022    /**
    023     *
    024     *
    025     *
    026     */
    027    public final class SetUtils {
    028        private SetUtils() {}
    029
    030        /**
    031         * Extracts the Strings from a Set that start with a given prefix.
    032         *
    033         * @param set    a Set of Strings (assumed to all be non-{@code null})
    034         * @param prefix the prefix to look for in the string set
    035         * @return an array of the matching strings from the given set
    036         */
    037        public static String[] prefixSet(final Set<String> set, final String prefix) {
    038            final Set<String> prefixSet = new HashSet<String>();
    039            for (final String str : set) {
    040                if (str.startsWith(prefix)) {
    041                    prefixSet.add(str);
    042                }
    043            }
    044            return prefixSet.toArray(new String[prefixSet.size()]);
    045        }
    046    }