Sorts a map based on value, returns sorted map with predictable iteration Initial - Java Collection Framework

Java examples for Collection Framework:Map

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Description

Sorts a map based on value, returns sorted map with predictable iteration Initial

Demo Code


//package com.java2s;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

public class Main {
    /**/* ww w  .j ava 2s . c  o  m*/
     * Sorts a map based on value, returns sorted map with predictable iteration
     * Initial code from: http://stackoverflow.com/questions/109383/how-to-sort-a-mapkey-value-on-the-values-in-java
     * @param map Map with assumed-Compable values
     * @param doReverse True if comparator's ordering should be reversed, False if normal
     * @return
     */
    public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(
            Map<K, V> map, boolean doReverse) {
        List<Map.Entry<K, V>> list = new LinkedList<Map.Entry<K, V>>(
                map.entrySet());

        Comparator<Map.Entry<K, V>> comparator = new Comparator<Map.Entry<K, V>>() {
            public int compare(Map.Entry<K, V> o1, Map.Entry<K, V> o2) {
                return (o1.getValue()).compareTo(o2.getValue());
            }
        };

        if (doReverse) {
            Collections.sort(list, Collections.reverseOrder(comparator));
        } else {
            Collections.sort(list, comparator);
        }

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

    /**
     * Sorts a map based on value, returns sorted map with predictable iteration
     * Initial code from: http://stackoverflow.com/questions/109383/how-to-sort-a-mapkey-value-on-the-values-in-java
     * @param map Map with assumed-Compable values
     * @return
     */
    public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(
            Map<K, V> map) {
        return sortByValue(map, false);
    }
}

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