Java Hashmap putAll() Method

hashmap puAll method

Java Hashmap

Hashmap class is a part of java.util package. In hashmap we can store key and value pairs , only with unique keys.If we try to insert a duplicate key it will replace the old value with new value. Many built-in methods are there in hashmap class which makes it easy to perform operations on them, like insertion , deletion and many more. One of those methods is Java Hashmap putAll() Method. 

To know more about Hashmap putAll() Method read the complete article.

Java Hashmap putAll() Method

The hashmap putAll() method is used to copy mappings of existing hashmap to the new hashmap. This method does not returns any value. Below in this page you can find it’s syntax, return values, parameters with detailed examples.

Syntax :


Return values :

This method does not return any value.

Hashmap putAll() Method Examples

Example :

import java.util.*;

public class Main
    public static void main (String[]args)

        // Creating an empty HashMap
        HashMap < String, Integer > hash_map_1 =
                new HashMap < String, Integer > ();

        // Mapping string values to int keys in a empty hashmap
        hash_map_1.put ("Maths", 80);
        hash_map_1.put ("English", 75);
        hash_map_1.put ("Hindi", 85);
        hash_map_1.put ("Science", 90);

        System.out.println("Original hashmap : " + hash_map_1);

       //copying mapping of existing hashmap to new hashmap
        HashMap < String, Integer > new_hashmap = new HashMap < String, Integer >() ;


        System.out.println("New hashmap : "+ new_hashmap);


Output :

Original hashmap : {Maths=80, English=75, Science=90, Hindi=85}
New hashmap : {Science=90, Maths=80, English=75, Hindi=85}

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