Sort HashMap in Java based on Values

Using AraryList with Comparator:

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.Map.Entry;

public class SortByKeyListComp {

     private static void printSortedMap(Map<String, Integer> map) {

           /* Create the entry set. */

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

          

           /* Create a list from EntrySet. */

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

          

           /* Sort List using the comparator. */

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

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

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

                }

           });

          

           /* Print data. */

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

                System.out.println("key#"+entry.getKey()+" value#"+entry.getValue());

           }

     }

    

     /**

      * Driver Method.

      */

     public static void main(String[] args) {

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

           map.put("geeks", 3);

           map.put("nerd", 2);

           map.put("test", 7);

          

           printSortedMap(map);

     }

}

Using TreeMap with Comparator:

import java.util.Comparator;

import java.util.HashMap;

import java.util.Map;

import java.util.TreeMap;

class ValueComparator implements Comparator {

     Map map;

     /* Set Map in Constructor. */

     public ValueComparator(Map map) {

           this.map = map;

     }

     /**

      * Compare the values using the default value of the Map.

      */

     public int compare(Object keyA, Object keyB) {

           Comparable valueA = (Comparable) map.get(keyA);

           Comparable valueB = (Comparable) map.get(keyB);

           return valueB.compareTo(valueA);

     }

}

public class SortByKeyTreeComp {

     public static Map sortByValue(Map unsortedMap) {

           /* Pass Map to ValueComparator so we can compare on the basic from defualt key.*/

           ValueComparator vc = new ValueComparator(unsortedMap);

           Map sortedMap = new TreeMap(vc);

           sortedMap.putAll(unsortedMap);

           return sortedMap;

     }

     public static void main(String[] args) {

           HashMap<String, Integer> map = new HashMap<String, Integer>();

           map.put("geeks", 3);

           map.put("nerd", 2);

           map.put("test", 7);

           System.out.println(map);

           Map sortedMap = sortByValue(map);

           System.out.println(sortedMap);

     }

}