Introduction: Why Java Is Needed for Automation Testing
Java is the most preferred programming language for automation testing coding interviews. In modern QA roles, interviewers don’t just ask theory—they expect candidates to write Java code, automate scenarios, and design frameworks in real time.
Why Java dominates automation testing interviews:
- Most automation frameworks are built using Java + Selenium
- Strong OOP concepts help design scalable frameworks
- Platform-independent (Windows, Linux, macOS)
- Seamless integration with UI, API, Database, CI/CD
- Huge demand for Java-based Automation Testers and SDETs
That’s why automation testing java coding interview questions focus heavily on hands-on coding, not just definitions.
Core Java Topics for Automation Testing (Coding-Focused)
Before Selenium coding, interviewers evaluate Core Java fundamentals.
1. OOP Concepts (Must for Coding Rounds)
- Class & Object
- Inheritance
- Polymorphism
- Encapsulation
- Abstraction
2. Java Collections
- List → ArrayList, LinkedList
- Set → HashSet
- Map → HashMap, LinkedHashMap
3. Exception Handling
- try, catch, finally
- Checked vs Unchecked exceptions
4. Multithreading (Basics)
- Thread class
- Runnable interface
5. Java 8 Features
- Streams
- Lambda expressions
- forEach()
Automation Testing Java Coding Interview Questions (Core Java)
Q1. Why is Java preferred for automation testing coding interviews?
Java allows interviewers to test OOP concepts, collections, exception handling, and automation logic together.
Q2. Write a Java program to demonstrate inheritance.
class Browser {
void open() {
System.out.println(“Browser opened”);
}
}
class Chrome extends Browser {
void test() {
System.out.println(“Testing application in Chrome”);
}
}
public class Demo {
public static void main(String[] args) {
Chrome c = new Chrome();
c.open();
c.test();
}
}
Output
Browser opened
Testing application in Chrome
Q3. What is polymorphism? Write a coding example.
class Login {
void login() {
System.out.println(“Login using password”);
}
void login(String otp) {
System.out.println(“Login using OTP”);
}
}
Q4. Write Java code for encapsulation.
class User {
private String username;
public void setUsername(String name) {
username = name;
}
public String getUsername() {
return username;
}
}
Q5. ArrayList vs LinkedList – code example.
List<String> list = new ArrayList<>();
list.add(“Java”);
list.add(“Selenium”);
System.out.println(list);
Output
[Java, Selenium]
Q6. Write a HashMap example.
HashMap<String,String> map = new HashMap<>();
map.put(“browser”, “chrome”);
System.out.println(map.get(“browser”));
Output
chrome
Q7. Checked vs Unchecked exception – example.
try {
int x = 10 / 0;
} catch (ArithmeticException e) {
System.out.println(“Exception handled”);
}
Output
Exception handled
Q8. Java 8 stream coding question.
List<Integer> nums = Arrays.asList(10,20,30);
nums.stream().filter(n -> n > 15).forEach(System.out::println);
Output
20
30
Q9. What is multithreading?
Executing multiple threads simultaneously to improve performance.
Q10. Thread vs Runnable – coding example.
class TestThread implements Runnable {
public void run() {
System.out.println(“Thread running”);
}
}
Selenium + Java Coding Interview Questions
Q11. Write Selenium code to open a browser.
WebDriver driver = new ChromeDriver();
driver.get(“https://example.com”);
Q12. Locate element using XPath.
driver.findElement(By.xpath(“//input[@id=’username’]”)).sendKeys(“admin”);
Q13. Handle dropdown using Selenium.
Select select = new Select(driver.findElement(By.id(“country”)));
select.selectByVisibleText(“India”);
Q14. Handle alert popup.
Alert alert = driver.switchTo().alert();
alert.accept();
Q15. Apply implicit and explicit wait.
driver.manage().timeouts().implicitlyWait(Duration.ofSeconds(10));
WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
wait.until(ExpectedConditions.visibilityOf(element));
Q16. Take screenshot in Selenium.
File src = ((TakesScreenshot)driver).getScreenshotAs(OutputType.FILE);
Q17. Find all links on a page.
List<WebElement> links = driver.findElements(By.tagName(“a”));
System.out.println(links.size());
Java Selenium Coding Challenges (Machine Test Level)
Q18. Automate login functionality.
Steps
- Open browser
- Enter username & password
- Click login
- Validate homepage
Q19. Handle dynamic elements using waits.
Use Explicit Wait to wait until element is visible.
Q20. Write Selenium code to scroll page.
JavascriptExecutor js = (JavascriptExecutor)driver;
js.executeScript(“window.scrollBy(0,500)”);
Real-Time Automation Interview Scenarios
Scenario 1: Page Object Model (POM) Design
Expected structure
- Base class → WebDriver setup
- Page classes → Locators & methods
- Test classes → Assertions
- Utilities → Config, waits, reports
Scenario 2: API + UI Validation
Steps
- Call login API
- Capture token
- Validate UI dashboard data
Scenario 3: Database Validation
Steps
- Fetch values from database
- Compare with UI values
JUnit Coding Interview Questions
Q21. What is JUnit?
JUnit is a unit testing framework for Java.
Q22. Common JUnit annotations.
- @Test
- @Before
- @After
TestNG Coding Interview Questions
Q23. What is TestNG?
TestNG is an advanced testing framework inspired by JUnit.
Q24. Write TestNG DataProvider example.
@DataProvider
public Object[][] loginData() {
return new Object[][] {
{“user1″,”pass1”},
{“user2″,”pass2”}
};
}
Q25. TestNG priority example.
@Test(priority = 1)
public void loginTest() {}
Selenium + Java + API Practical Coding Example
Response response = RestAssured.get(“/users”);
System.out.println(response.getStatusCode());
Output
200
Framework Design Questions (Coding Interviews)
Q26. What is Hybrid Framework?
Combination of POM + Data-Driven + Keyword-Driven frameworks.
Q27. What is Cucumber?
BDD framework using Gherkin syntax (Given-When-Then).
Q28. CI/CD tools used in automation?
- Jenkins
- GitHub Actions
- Azure DevOps
Common Mistakes in Automation Testing Java Coding Interviews
- Weak Core Java fundamentals
- Writing unstructured code
- Hard-coded test data
- Ignoring waits and exceptions
- Poor framework understanding
1-Page Revision Table / Notes
| Area | Key Focus |
| Core Java | OOP, Collections, Streams |
| Selenium | Locators, Waits |
| TestNG/JUnit | Annotations, DataProvider |
| Framework | POM, Hybrid, Cucumber |
| API | Rest Assured |
| CI/CD | Jenkins |
FAQs – Automation Testing Java Coding Interview Questions
Q1. Are coding questions mandatory in automation interviews?
Yes, most automation interviews include Java + Selenium coding.
Q2. What level of Java is required for automation testing?
Strong Core Java fundamentals are sufficient.
Q3. Is Selenium coding asked in machine rounds?
Yes, Selenium coding is very common.
Q4. Do automation testers need API testing skills?
Yes, modern automation roles expect API knowledge.