Top 50 Java MCQ Questions – Master Java for Interviews & Exams

Multiple-choice questions are a quick way to test and reinforce Java fundamentals. Here's a sample set covering core concepts.

1. Which of these is not a Java primitive type?

a) int b) float c) String d) boolean
Answer: c) String — it's a class, not a primitive type.

2. What is the default value of a boolean variable in Java?

a) true b) false c) 0 d) null
Answer: b) false

3. Which keyword is used to inherit a class in Java?

a) implements b) extends c) inherits d) super
Answer: b) extends

4. Which collection class allows duplicate elements but maintains insertion order?

a) HashSet b) TreeSet c) ArrayList d) HashMap
Answer: c) ArrayList

5. Which method is the entry point of a Java application?

a) start() b) run() c) main() d) init()
Answer: c) main()

6. Which of these is used to handle exceptions in Java?

a) try-catch b) if-else c) for-loop d) switch
Answer: a) try-catch

7. What is the size of an int in Java?

a) 8 bits b) 16 bits c) 32 bits d) 64 bits
Answer: c) 32 bits

8. Which keyword prevents a class from being subclassed?

a) static b) final c) private d) abstract
Answer: b) final

9. Which interface must a class implement to be used with the "for-each" loop?

a) Comparable b) Iterable c) Runnable d) Serializable
Answer: b) Iterable

10. Which of these is used to create a thread pool?

a) new Thread() b) ExecutorService c) Runnable d) ThreadGroup
Answer: b) ExecutorService