Introduction: Why Java Is Needed for Automation Testing
Java is one of the most frequently tested languages in coding interviews, especially for automation testing and SDET roles. In most companies, java coding test interview questions focus on two things:
- Problem-solving ability using Core Java
- Applying Java logic to automation testing scenarios
Java is widely used in automation testing because it:
- Supports object-oriented programming, enabling reusable automation code
- Integrates seamlessly with Selenium WebDriver
- Works well with JUnit, TestNG, Maven, Jenkins
- Handles API testing, database validation, and file handling
- Scales efficiently for enterprise automation frameworks
Coding tests often include output-based questions, logic problems, and small automation-related programs.
Core Java Topics for Testing (Coding Test Focus)
1. Object-Oriented Programming (OOP)
- Encapsulation for reusable methods
- Inheritance for base classes
- Polymorphism with WebDriver
- Abstraction using interfaces
2. Java Collections
- List, Set, Map operations
- HashMap for test data
- Iteration and filtering logic
3. Multithreading
- Thread vs Runnable
- Parallel execution concepts
- Thread safety basics
4. Exception Handling
- Checked vs unchecked exceptions
- try-catch-finally
- Custom exceptions
5. Java Streams
- filter(), map(), reduce()
- Data validation
- Clean and concise logic
Java Coding Test Interview Questions & Detailed Answers
Core Java Coding Questions
1. Reverse a String
String s = “Java”;
String rev = “”;
for(int i = s.length() – 1; i >= 0; i–) {
rev = rev + s.charAt(i);
}
System.out.println(rev);
Output:
avaJ
2. Check Palindrome String
String s = “madam”;
String rev = new StringBuilder(s).reverse().toString();
System.out.println(s.equals(rev));
Output:
true
3. Find Factorial of a Number
int n = 5;
int fact = 1;
for(int i = 1; i <= n; i++) {
fact *= i;
}
System.out.println(fact);
Output:
120
4. Print Fibonacci Series
int a = 0, b = 1;
for(int i = 1; i <= 5; i++) {
System.out.print(a + ” “);
int c = a + b;
a = b;
b = c;
}
Output:
0 1 1 2 3
5. Find Largest Number in Array
int[] arr = {10, 45, 3, 99};
int max = arr[0];
for(int n : arr) {
if(n > max) max = n;
}
System.out.println(max);
Output:
99
6. Count Duplicate Characters
String s = “automation”;
Map<Character, Integer> map = new HashMap<>();
for(char c : s.toCharArray()) {
map.put(c, map.getOrDefault(c, 0) + 1);
}
System.out.println(map);
Output (example):
{a=2, u=1, t=2, o=2, m=1, i=1, n=1}
7. Remove Duplicate Elements from List
List<Integer> list = Arrays.asList(1,2,2,3,3);
Set<Integer> set = new HashSet<>(list);
System.out.println(set);
Output:
[1, 2, 3]
8. Difference Between == and equals()
String a = new String(“Java”);
String b = new String(“Java”);
System.out.println(a == b);
System.out.println(a.equals(b));
Output:
false
true
9. Exception Handling Example
try {
int a = 10 / 0;
} catch (ArithmeticException e) {
System.out.println(“Exception handled”);
}
Output:
Exception handled
10. Read Data from File
File file = new File(“test.txt”);
Scanner sc = new Scanner(file);
while(sc.hasNextLine()) {
System.out.println(sc.nextLine());
}
Java Coding Test Questions (Automation Context)
11. Launch Browser and Print Title
WebDriver driver = new ChromeDriver();
driver.get(“https://example.com”);
System.out.println(driver.getTitle());
driver.quit();
Expected Output:
Page title printed
12. Click Login Button Using CSS Selector
driver.findElement(By.cssSelector(“button.login”)).click();
13. Explicit Wait Example
WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
wait.until(ExpectedConditions.visibilityOfElementLocated(By.id(“username”)));
Java Selenium Coding Challenges
Locators
14. Types of Selenium Locators
- ID
- Name
- ClassName
- XPath
- CSS Selector
Dynamic XPath
//input[contains(@id,’email’)]
Waits Difference
| Implicit Wait | Explicit Wait |
| Global | Element-specific |
| Less control | More reliable |
Real-Time Interview Scenarios
Scenario 1: Page Object Model (POM)
Problem:
Design a login page using POM.
public class LoginPage {
WebDriver driver;
By username = By.id(“user”);
By password = By.id(“pass”);
public LoginPage(WebDriver driver) {
this.driver = driver;
}
public void login(String u, String p) {
driver.findElement(username).sendKeys(u);
driver.findElement(password).sendKeys(p);
}
}
Scenario 2: API + Database Validation
Approach:
- Call API using RestAssured
- Validate status code
- Fetch data from DB using JDBC
- Compare API and DB values
JUnit Coding Test Interview Questions
15. Simple JUnit Test
@Test
public void testAdd() {
assertEquals(5, 2 + 3);
}
Common JUnit Annotations
| Annotation | Purpose |
| @Test | Test case |
| @BeforeEach | Runs before test |
| @AfterEach | Runs after test |
TestNG Coding Test Questions
16. TestNG Priority Example
@Test(priority = 1)
public void loginTest() {}
DataProvider Example
@DataProvider
public Object[][] data() {
return new Object[][] {{“admin”,”pass”}};
}
Selenium + Java + API Practical Example
Response response = RestAssured.get(“/users/1”);
Assert.assertEquals(response.getStatusCode(), 200);
Framework Design Coding Test Questions
17. What is Hybrid Framework?
Combination of:
- Page Object Model
- Data-Driven framework
- Keyword-Driven framework
18. CI/CD Tools Used
- Git
- Maven
- Jenkins
- GitHub Actions
19. Role of Cucumber
- BDD approach
- Feature files
- Step definitions
Common Mistakes in Java Coding Interviews
- Weak Core Java fundamentals
- Ignoring edge cases
- Overusing Thread.sleep()
- Poor exception handling
- No clarity on framework design
1-Page Java Coding Revision Notes
| Topic | Focus |
| Java Basics | Loops, Strings |
| Collections | List, Map |
| Selenium | Locators, Waits |
| Testing | JUnit, TestNG |
| Framework | POM, Hybrid |
FAQs – Java Coding Test Interview Questions
Q1. Are Java coding tests difficult?
No, if fundamentals and logic are strong.
Q2. What type of questions are asked most?
String manipulation, arrays, collections, and automation basics.
Q3. Is Selenium coding mandatory?
Yes, for automation roles.
Q4. How many programs should I practice?
At least 200+ java coding test interview questions.