Tuesday, September 24, 2013

LinkedHashMap Example in Java

LinkedHashMap is used for Key-Value concepts. when we require to store values based on Key then LinkedHashMap is for You !But It maintains insertion order while HashMap does not.

About LinkedHashMap:
  • It extends HashMap class and Implements Map Interface
  • It maintain insertion order
  • Allows null as Key and Values also
  • Contains unique elements Only
You may want to refer to :

If You observe output of LinkedHashMap example as below, Output is same in sequence we inserted elements because LinkedHashMap does maintain Insertion Order while HashMap does not.

Java LinkedHashMap Example :
package com.anuj.basic;

import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

 * @author Anuj
 * Maintain Insertion Order
 * Allow Null
public class LinkedHashMapOperations {

 public static void main(String[] args) {
  LinkedHashMap hashMap = new LinkedHashMap();
  hashMap.put("David", "3");
  hashMap.put("David", "3");
  Set set = hashMap.entrySet();
  Iterator iterator = set.iterator();
   Map.Entry entry = (Map.Entry)iterator.next();
   System.out.println("Key:"+entry.getKey() + " Value:"+entry.getValue());


Output :
Key:Anuj Value:1
Key:Zvika Value:2
Key:David Value:3
Key:null Value:null

Author : Anuj Patel
Blog : http://goldenpackagebyanuj.blogspot.in/