How To Update A Value, Given A Key In A Hashmap?

To update a value in a HashMap in Java, you can use the put() method to overwrite the existing value associated with a given key. Here’s an example:

import java.util.HashMap;

public class HashMapUpdateExample {
    public static void main(String[] args) {
        // Create a HashMap
        HashMap<String, Integer> map = new HashMap<>();

        // Add key-value pairs to the HashMap
        map.put("key1", 10);
        map.put("key2", 20);
        map.put("key3", 30);
        System.out.println("Before update: " + map);

        // Update value for a given key
        map.put("key2", 50);

        System.out.println("After update: " + map);


Before update: {key1=10, key2=20, key3=30}
After update: {key1=10, key2=50, key3=30}

In the above example, the value associated with the key "key2" is updated from 20 to 50 using the put() method.

About the Author Rex

I'm a passionate tech blogger with an insatiable love for programming! From my early days tinkering with code, I've delved into web dev, mobile apps, and AI. Sharing insights and tutorials with the world is my joy, connecting me to a global community of like-minded tech enthusiasts. Python holds a special place in my heart, but I embrace all challenges. Constantly learning, I attend tech conferences, contribute to open-source projects, and engage in code review sessions. My ultimate goal is to inspire the next generation of developers and contribute positively to the ever-evolving tech landscape. Let's code together!