Java: How to Add two Maps with example

If you have two or more Map collections in Java and you want to add them, make use of there putAll method.


import java.util.HashMap;
import java.util.Map;

 * Example: Add two Maps
 * Author:
 * Date: 3nd May 2023
 * Version: v1.0
public class CombineMapsJava {

    public static void main(String[] args) {

        Map<String, Integer> countriesMap1 = new HashMap<>();
        countriesMap1.put("China", 1);
        countriesMap1.put("Japan", 2);

        Map<String, Integer> countriesMap2 = new HashMap<>();
        countriesMap2.put("Canada", 3);
        countriesMap2.put("USA", 4);

        Map<String, Integer> countriesMap = new HashMap<>();



{Canada=3, USA=4, China=1, Japan=2}


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Rakesh (He/Him) is a seasoned developer with over 10 years of experience in web and app development, and a deep knowledge of operating systems. Author of insightful How-To articles for Code2care.

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