Introduction: Why Java Is Needed for Automation Testing
In most companies, the first screening round for automation roles is a Java interview questions online test. These online tests check whether a candidate can:
- Understand Core Java concepts
- Write basic to intermediate Java code
- Apply Java knowledge to automation testing
- Solve scenario-based MCQs and coding problems
- Identify correct output and fix errors
Java is widely used in automation because it integrates seamlessly with Selenium WebDriver, TestNG, JUnit, REST APIs, databases, and CI/CD tools. This article prepares you for online Java tests, not just theory interviews.
Primary Keyword: java interview questions online test
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Core Java Topics for Testing (Online Test Focus)
Online tests usually evaluate fundamentals + practical understanding.
1. OOP Concepts (High Priority)
| Concept | Tested In Online Exams |
| Encapsulation | MCQs + code output |
| Inheritance | Code snippets |
| Polymorphism | Output-based questions |
| Abstraction | Interface questions |
2. Collections Framework
Frequently tested through:
- Output prediction
- Error identification
- Usage-based questions
Common classes:
- ArrayList
- HashSet
- HashMap
- Iterator
3. Multithreading (Basics)
Mostly tested as:
- Conceptual MCQs
- Output-based questions
4. Exception Handling
Online tests check:
- Checked vs unchecked exceptions
- try-catch-finally logic
- Compilation vs runtime errors
5. Java 8 Streams & Lambda
Used in:
- Filtering collections
- Reducing loops
- Output-based questions
Java Interview Questions Online Test (With Answers)
Core Java MCQs & Conceptual Questions
1. What is Java?
Answer:
Java is an object-oriented, platform-independent programming language.
2. Which component makes Java platform independent?
Answer:
JVM (Java Virtual Machine)
3. Difference between JDK, JRE, and JVM?
| Component | Purpose |
| JVM | Executes bytecode |
| JRE | JVM + libraries |
| JDK | JRE + dev tools |
4. Which keyword is used for inheritance?
Answer:
extends
5. What is polymorphism?
Answer:
Ability of an object to take multiple forms.
6. Predict the output:
String a = “Java”;
String b = “Java”;
System.out.println(a == b);
Answer:
true
Explanation:
String literals are stored in the String constant pool.
7. Predict the output:
String a = new String(“Java”);
String b = new String(“Java”);
System.out.println(a == b);
Answer:
false
8. Which keyword prevents inheritance?
Answer:
final
9. Can we override static methods?
Answer:
No, static methods cannot be overridden.
10. What is an interface?
Answer:
An interface contains abstract methods and supports multiple inheritance.
Collections Online Test Questions
11. Difference between Array and ArrayList?
| Array | ArrayList |
| Fixed size | Dynamic size |
| Faster | Slightly slower |
12. Which collection does not allow duplicates?
Answer:
Set
13. Predict the output:
Set<Integer> set = new HashSet<>();
set.add(10);
set.add(10);
System.out.println(set.size());
Answer:
1
14. Which collection stores key-value pairs?
Answer:
Map
15. HashMap allows null values?
Answer:
Yes, one null key and multiple null values.
16. Example of HashMap in automation:
Map<String, String> login = new HashMap<>();
login.put(“username”, “admin”);
login.put(“password”, “test123”);
Exception Handling Online Test Questions
17. What is an exception?
Answer:
An abnormal event that interrupts program execution.
18. Which is a checked exception?
Answer:
IOException
19. Which is an unchecked exception?
Answer:
NullPointerException
20. Predict the output:
try {
int a = 10 / 0;
} catch (Exception e) {
System.out.println(“Exception”);
}
Answer:
Exception
21. Will finally block execute if exception occurs?
Answer:
Yes.
File Handling Questions (Online Coding Test)
22. Read a file in Java:
BufferedReader br =
new BufferedReader(new FileReader(“data.txt”));
String line;
while((line = br.readLine()) != null) {
System.out.println(line);
}
Expected Output:
Prints file content line by line.
Multithreading Online Test Questions
23. What is multithreading?
Answer:
Executing multiple threads simultaneously.
24. Why multithreading is used in automation?
Answer:
For parallel execution of test cases.
25. Which TestNG feature supports parallel execution?
Answer:
parallel attribute in XML.
Selenium WebDriver Online Test Questions
26. What is Selenium?
Answer:
Selenium is an open-source automation testing tool for web applications.
27. Components of Selenium?
- Selenium WebDriver
- Selenium IDE
- Selenium Grid
28. What is WebDriver?
Answer:
WebDriver is an interface used to automate browsers.
29. Types of locators in Selenium?
- ID
- Name
- XPath
- CSS Selector
30. Fastest locator?
Answer:
ID locator.
31. Difference between findElement and findElements?
| Method | Result |
| findElement | Exception |
| findElements | Empty list |
Java Selenium Coding Challenges (Online Test Style)
Challenge 1: Print page title
WebDriver driver = new ChromeDriver();
driver.get(“https://example.com”);
System.out.println(driver.getTitle());
Challenge 2: Explicit wait example
WebDriverWait wait =
new WebDriverWait(driver, Duration.ofSeconds(10));
wait.until(ExpectedConditions
.visibilityOfElementLocated(By.id(“submit”)));
Challenge 3: Count links on page
List<WebElement> links =
driver.findElements(By.tagName(“a”));
System.out.println(links.size());
Framework Design Online Test Questions
32. What is Page Object Model?
Answer:
POM separates page elements and test logic.
33. Advantages of POM?
- Code reusability
- Easy maintenance
- Readable tests
34. What is Hybrid Framework?
Answer:
Combination of POM, TestNG, utilities, and data-driven approach.
35. What is Cucumber?
Answer:
Cucumber supports BDD using Gherkin language.
36. CI/CD tools used in automation?
Answer:
Jenkins, GitHub Actions, GitLab CI.
TestNG Interview Questions (Online Test)
37. What is TestNG?
Answer:
TestNG is a testing framework inspired by JUnit.
38. Important TestNG annotations?
- @Test
- @BeforeMethod
- @AfterMethod
39. How to group tests?
@Test(groups = “smoke”)
40. How to retry failed tests?
Answer:
Using IRetryAnalyzer.
JUnit Online Test Questions
41. What is JUnit?
Answer:
JUnit is a unit testing framework for Java.
42. Difference between JUnit and TestNG?
| Feature | TestNG | JUnit |
| Parallel | Yes | Limited |
| Groups | Yes | No |
Selenium + Java + API Practical Example
Response res = RestAssured.get(“/users”);
int status = res.getStatusCode();
System.out.println(status);
Used to validate backend APIs in automation.
Real-Time Interview Scenarios (Online Assessment)
Scenario 1: Test fails randomly
Solution:
- Use explicit waits
- Avoid Thread.sleep
- Improve locators
Scenario 2: Script passes locally, fails in CI
Solution:
- Use headless browser
- Handle environment configs
- Avoid hard-coded paths
Common Mistakes in Java Online Tests
❌ Ignoring output-based questions
❌ Weak OOP basics
❌ Confusing checked vs unchecked exceptions
❌ Not reading question carefully
❌ Poor time management
1-Page Java Online Test Revision Table
| Topic | Focus |
| OOP | Encapsulation, Polymorphism |
| Collections | List, Set, Map |
| Selenium | Locators, Waits |
| Java | Exceptions |
| Framework | POM |
| TestNG | Annotations |
FAQs – Java Interview Questions Online Test
Q1. What is tested in Java online tests?
Core Java, OOP, Collections, Selenium basics.
Q2. Are coding questions included?
Yes, basic to intermediate coding.
Q3. Are automation frameworks tested?
Yes, POM and Hybrid framework basics.
Q4. How to prepare best?
Practice output-based questions and real code.