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
018package org.apache.commons.collections4.properties;
019
020import java.util.ArrayList;
021import java.util.Collections;
022import java.util.Enumeration;
023import java.util.List;
024import java.util.Properties;
025import java.util.Set;
026
027import org.apache.commons.collections4.iterators.IteratorEnumeration;
028
029/**
030 * A drop-in replacement for {@link Properties} for sorting keys.
031 * <p>
032 * Overrides {@link Properties#keys()} to sort keys. Allows other methods on the superclass to work with sorted keys.
033 * </p>
034 *
035 * @since 4.2
036 */
037public class SortedProperties extends Properties {
038
039    private static final long serialVersionUID = 1L;
040
041    @Override
042    public synchronized Enumeration<Object> keys() {
043        final Set<Object> keySet = keySet();
044        final List<String> keys = new ArrayList<>(keySet.size());
045        for (final Object key : keySet) {
046            keys.add(key.toString());
047        }
048        Collections.sort(keys);
049        return new IteratorEnumeration<Object>(keys.iterator());
050    }
051}