CodesJava

Easy learning with example program codes

how to copy map content to another hashmap in java?


HashMap

HashMap extends AbstractMap class and implements the Map interface. It contains the elements in key-value pair form. It not maintains any order for its elements. It not allowed duplicate key. A HashMap can have only one null key and multiple null values.

We can use putAll() method to copy map content to another hashmap in java.

putAll(Map m): Puts all the entries from m into this map.
Syntax: public void putAll(Map m)

Example

package com.codesjava;
 
import java.util.HashMap;
 
public class Test {
  public static void main(String args[]){
	//Create HashMap object.
	HashMap<Integer, String> hashMap = new HashMap<Integer, String>();
 
	//Add objects to the HashSet.
	hashMap.put(4, "Roxy");
	hashMap.put(2, "Sunil");
	hashMap.put(5, "Sandy");
	hashMap.put(1, "Munish");
	hashMap.put(3, "Pardeep");
 	//Print the HashMap object.
	System.out.println("HashMap elements:");
	System.out.println(hashMap);
 
	//Create a sub map
	HashMap<Integer, String> subMap = new HashMap<Integer, String>();
	//Add elements
        subMap.put(6, "Ajay");
        subMap.put(7, "Vikas");
        hashMap.putAll(subMap);
 
        //Print the HashMap object.
      	System.out.println("HashMap elements:");
      	System.out.println(hashMap);
  }
}

Output

HashMap elements:
{1=Munish, 2=Sunil, 3=Pardeep, 4=Roxy, 5=Sandy}
HashMap elements:
{1=Munish, 2=Sunil, 3=Pardeep, 4=Roxy, 5=Sandy, 6=Ajay, 7=Vikas}


Copyright © 2018 CodesJava DMCA.com Protection Status SiteMap