Sort a map according to its values in ascending order when asc=true and i descending order otherwise. - Java java.util

Java examples for java.util:Map Sort

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Description

Sort a map according to its values in ascending order when asc=true and i descending order otherwise.

Demo Code


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

public class Main {
    /**/*from   w w  w  . j a v  a2  s  .c o m*/
     * Sort a map according to its values in ascending order when asc=true and i descending order otherwise.
     * @param unsortedMap 
     * @param asc
     * @return
     */
    public static Map<String, Integer> sortUsingComparator(
            Map<String, Integer> unsortedMap, final boolean asc) {

        // Convert Map to List
        List<Map.Entry<String, Integer>> list = new LinkedList<Map.Entry<String, Integer>>(
                unsortedMap.entrySet());

        // Sort a list using custom comparator, to compare the Map values
        Collections.sort(list,
                new Comparator<Map.Entry<String, Integer>>() {
                    public int compare(Map.Entry<String, Integer> o1,
                            Map.Entry<String, Integer> o2) {
                        if (asc) {
                            return (o1.getValue()).compareTo(o2.getValue());
                        } else {
                            return -1
                                    * (o1.getValue()).compareTo(o2
                                            .getValue());
                        }
                    }
                });

        // Convert the sorted map back to a Map
        Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>();
        for (Iterator<Map.Entry<String, Integer>> it = list.iterator(); it
                .hasNext();) {
            Map.Entry<String, Integer> entry = it.next();
            sortedMap.put(entry.getKey(), entry.getValue());
        }
        return sortedMap;
    }
}

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