Write a Java program to demonstrate HashMap operations (put, get, iterate, check key/value).

Q: Write a Java program to demonstrate HashMap operations (put, get, iterate, check key/value).

HashMap Operations in Java java import java.util.HashMap; import java.util.Map; public class HashMapOperations { public static void main(String args) { // Create HashMap HashMap<String, String map = new HashMap<(); // put() - add key-value pairs map.put("browser", "Chrome"); map.put("environment", "Staging"); map.put("username", "admin@test.com"); map.put("password", "Admin@123"); map.put("baseUrl", "https://staging.example.com"); System.out.println("Map: " + map); System.out.println("Size: " + map.size()); // get() - retrieve by key System.out.println("Browser: " + map.get("browser")); // con

Answer

HashMap Operations in Java

Java

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

public class HashMapOperations {
    public static void main(String[] args) {

        // Create HashMap
        HashMap<String, String> map = new HashMap<>();

        // put() - add key-value pairs
        map.put("browser",     "Chrome");
        map.put("environment", "Staging");
        map.put("username",    "admin@test.com");
        map.put("password",    "Admin@123");
        map.put("baseUrl",     "https://staging.example.com");

        System.out.println("Map: " + map);
        System.out.println("Size: " + map.size());

        // get() - retrieve by key
        System.out.println("Browser: " + map.get("browser"));

        // containsKey() and containsValue()
        System.out.println("Has 'browser' key: " + map.containsKey("browser"));
        System.out.println("Has 'Chrome' value: " + map.containsValue("Chrome"));

        // Update value
        map.put("browser", "Firefox");
        System.out.println("Updated browser: " + map.get("browser"));

        // remove()
        map.remove("password");
        System.out.println("After remove: " + map);

        // Iterate using entrySet()
        System.out.println("\n--- All key-value pairs ---");
        for (Map.Entry<String, String> entry : map.entrySet()) {
            System.out.println(entry.getKey() + " → " + entry.getValue());
        }

        // Iterate keys only
        System.out.println("\n--- Keys only ---");
        for (String key : map.keySet()) {
            System.out.println(key);
        }
    }
}

Output

CODE

Map: {browser=Chrome, environment=Staging, username=admin@test.com, ...}
Size: 5
Browser: Chrome
Has 'browser' key: true
Has 'Chrome' value: true
Updated browser: Firefox
After remove: {browser=Firefox, environment=Staging, ...}

--- All key-value pairs ---
browser → Firefox
environment → Staging
username → admin@test.com
baseUrl → https://staging.example.com

Key HashMap Methods

Method	Purpose
`put(key, value)`	Add/update key-value
`get(key)`	Get value by key (null if missing)
`getOrDefault(key, default)`	Get value or default
`containsKey(key)`	Check if key exists
`containsValue(value)`	Check if value exists
`remove(key)`	Delete entry
`size()`	Number of entries
`keySet()`	Set of all keys
`values()`	Collection of all values
`entrySet()`	Set of all key-value pairs
`isEmpty()`	Check if empty
`clear()`	Remove all entries

Automation Testing Relevance

Java

// Store test data per environment
HashMap<String, String> testData = new HashMap<>();
testData.put("dev_url",     "https://dev.example.com");
testData.put("staging_url", "https://staging.example.com");

String env = System.getProperty("env", "staging");
driver.get(testData.get(env + "_url"));

// Store expected vs actual results
HashMap<String, String> results = new HashMap<>();
results.put("Title",  driver.getTitle());
results.put("URL",    driver.getCurrentUrl());
results.put("Header", driver.findElement(By.h1).getText());