Sort or order a HashMap or TreeSet or any map item by value. Write a comparator

which compares by value, not by key. Entry class might hleps you here.

package govind;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Set;

public class HashMapSortingBasedOnValue{

            public static void main(String[] args) {

                        Map<String, Integer> m=new HashMap<>();

                        m.put("one", 1);

                        m.put("five", 5);

                        m.put("two", 2);

                        m.put("four", 4);

                        m.put("three", 3);

                        System.out.println("-----------Before Soring Map Value-----------");

                        System.out.println(m);

                        System.out.println("---------------After Sorting(based on value)----------------");

            Set<Entry<String, Integer>> set = m.entrySet();

            List<Entry<String, Integer>> l=new ArrayList<>(set);

            Collections.sort(l, new Comparator<Map.Entry<String, Integer>>() {

      @Override

                        public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {

           

                                    return (o1.getValue()).compareTo(o2.getValue());

                        }

            });

                System.out.println("--------------iterate through iterator---------------");

                        Iterator<Entry<String, Integer>> it = l.iterator();

                        while(it.hasNext())

                        {

                                    Entry<String, Integer> kk = it.next();

                                    System.out.println(kk.getKey()+" "+kk.getValue());

                        }

                       

                        System.out.println("-----------Through  for each loop------------");

                         for(Map.Entry<String, Integer> entry:l){

                        System.out.println(entry.getKey()+" ==== "+entry.getValue());

                    }

            }

}

o/p:----------------------------

-----------Before Soring Map Value-----------

{four=4, one=1, five=5, two=2, three=3}

---------------After Sorting( based on value) ----------------

--------------iterate through iterator---------------

one 1

two 2

three 3

four 4

five 5

-----------Through  for each loop------------

one ==== 1

two ==== 2

three ==== 3

four ==== 4

five ==== 5