    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.AbstractMap;
    021import java.util.AbstractMap.SimpleEntry;
    022import java.util.Enumeration;
    023import java.util.LinkedHashSet;
    024import java.util.Map;
    025import java.util.Properties;
    026import java.util.Set;
    027import java.util.stream.Collectors;
    028import java.util.stream.Stream;
    029
    030import org.apache.commons.collections4.iterators.IteratorEnumeration;
    031
    032/**
    033 * A drop-in replacement for {@link Properties} for sorting keys.
    034 * <p>
    035 * Overrides {@link Properties#keys()} to sort keys. Allows other methods on the superclass to work with sorted keys.
    036 * </p>
    037 *
    038 * @see SortedPropertiesFactory#INSTANCE
    039 * @since 4.2
    040 */
    041public class SortedProperties extends Properties {
    042
    043    private static final long serialVersionUID = 1L;
    044
    045    /**
    046     * Constructs a new instance.
    047     */
    048    public SortedProperties() {
    049        // empty
    050    }
    051
    052    @Override
    053    public Set<Map.Entry<Object, Object>> entrySet() {
    054        final Stream<SimpleEntry<Object, Object>> stream = sortedKeys().map(k -> new AbstractMap.SimpleEntry<>(k, getProperty(k)));
    055        return stream.collect(Collectors.toCollection(LinkedHashSet::new));
    056    }
    057
    058    @Override
    059    public synchronized Enumeration<Object> keys() {
    060        return new IteratorEnumeration<>(sortedKeys().collect(Collectors.toList()).iterator());
    061    }
    062
    063    private Stream<String> sortedKeys() {
    064        return keySet().stream().map(Object::toString).sorted();
    065    }
    066}