Java Map Sort sortByValue(Map map, boolean descending)

Description

Sorts a map by its values.

License

Open Source License

Parameter

Parameter	Description
map	a map
descending	if <tt>true</tt> the map is sorted descending, otherwise ascending
K	the key type
V	the value type

Return

a new map

Declaration

public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map, boolean descending) 

Method Source Code

//package com.java2s;
/* *********************************************************************** *
 * project: org.matsim.*//www . j  a v a  2 s .c  o  m
 * CollectionUtils.java
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 * copyright       : (C) 2011 by the members listed in the COPYING,        *
 *                   LICENSE and WARRANTY file.                            *
 * email           : info at matsim dot org                                *
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *   See also COPYING, LICENSE and WARRANTY file                           *
 *                                                                         *
 * *********************************************************************** */

import java.util.*;
import java.util.Map.Entry;

public class Main {
    /**
     * Sorts a map by its values in ascending order.
     *
     * @param map a map
     * @param <K> the key type
     * @param <V> the value type
     * @return a new map
     */
    public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map) {
        return sortByValue(map, false);
    }

    /**
     * Sorts a map by its values.
     *
     * @param map        a map
     * @param descending if <tt>true</tt> the map is sorted descending, otherwise ascending
     * @param <K>        the key type
     * @param <V>        the value type
     * @return a new map
     */
    public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map, boolean descending) {
        int s2 = 1;
        if (descending)
            s2 = -1;
        final int sign = s2;

        List<Map.Entry<K, V>> list = new LinkedList<>(map.entrySet());

        Collections.sort(list, new Comparator<Map.Entry<K, V>>() {

            @Override
            public int compare(Entry<K, V> o1, Entry<K, V> o2) {
                return sign * o1.getValue().compareTo(o2.getValue());
            }
        });

        Map<K, V> sorted = new LinkedHashMap<>();
        for (Map.Entry<K, V> entry : list) {
            sorted.put(entry.getKey(), entry.getValue());
        }

        return sorted;
    }
}

Related

1. sortByValue(Map map)
2. sortByValue(Map map)
3. sortByValue(Map map)
4. sortByValue(Map map)
5. sortByValue(Map map)
6. sortByValue(Map map, final boolean asc)
7. sortByValue(Map map)
8. sortByValue(Map map)
9. sortByValueAscending(Map map)