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Java HashMap put() Method with Example

HashMap Class put() method: Here, we are going to learn about the put() method of HashMap Class with its syntax and example.
Submitted by Preeti Jain, on March 04, 2020

HashMap Class put() method

• put() method is available in java.util package.
• put() method is used to link the given value element with the given key element in this HashMap.
• put() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• put() method does not throw an exception at the time of replacing the old element if exists.

Syntax:

    public Value put(Key key_ele, Value val_ele);

Parameter(s):

• Key key_ele – represents the key element with which the given value element is to be linked.
• Value val_ele – represents the value element with which the given key element is to be linked.

Return value:

The return type of the method is Value, it returns the old element linked with the given key element when exists otherwise it returns null.

Example:

// Java program to demonstrate the example 
// of Value put(Key key_ele, Value val_ele)
// method of HashMap 

import java.util.*;

public class PutOfHashMap {
    public static void main(String[] args) {
        // Instantiates a HashMap object
        Map < Integer, String > map = new HashMap < Integer, String > ();

        // By using put() method is to add
        // key-value pairs in a HashMap
        map.put(10, "C");
        map.put(20, "C++");
        map.put(50, "JAVA");
        map.put(40, "PHP");
        map.put(30, "SFDC");

        // Display HashMap
        System.out.println("HashMap: " + map);

        // By using put() method is to
        // replace the existing value associated
        // for the given key element with the
        // new value element

        map.put(50, "Microservices");

        // Display Modified HashMap
        System.out.print("HashMap: " + map);
    }
}

Output

HashMap: {50=JAVA, 20=C++, 40=PHP, 10=C, 30=SFDC}
HashMap: {50=Microservices, 20=C++, 40=PHP, 10=C, 30=SFDC}