October 6, 2018

Sreekanth B

Write a Program to Sort a Map By Value Java Program

Program:

Write a program to sort a map by value.

Description:

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.

Code:

package com.java2novice.algos;

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 OrderByValue {

    public static void main(String a[]){
        Map<String, Integer> map = new HashMap<String, Integer>();
        map.put("java", 20);
        map.put("C++", 45);
        map.put("Java2Novice", 2);
        map.put("Unix", 67);
        map.put("MAC", 26);
        map.put("Why this kolavari", 93);
        Set<Entry<String, Integer>> set = map.entrySet();
        List<Entry<String, Integer>> list = new ArrayList<Entry<String, Integer>>(set);
        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() );
            }
        } );
        for(Map.Entry<String, Integer> entry:list){
            System.out.println(entry.getKey()+" ==== "+entry.getValue());
        }
    }
}

Output:

Why this kolavari ==== 93
Unix ==== 67
C++ ==== 45
MAC ==== 26
java ==== 20
Java2Novice ==== 2

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