Are you preparing for a Java certification or interview? Testing your knowledge with Java MCQ questions and answers is a great way to assess your understanding of core concepts. Below are some commonly asked multiple-choice questions along with explanations to help you strengthen your Java skills.
- What is the output of the following code?
java
Copy
public class Main {
public static void main(String[] args) {
System.out.println(10 + 20 + “Java”);
}
}
Options:
- A) 30Java
- B) 1020Java
- C) Compilation Error
- D) Runtime Error
Answer: A) 30Java
Explanation: The + operator performs addition first (10 + 20 = 30) and then concatenates with “Java”.
- Which keyword is used to prevent method overriding in Java?
Options:
- A) static
- B) final
- C) abstract
- D) private
Answer: B) final
Explanation: The final keyword prevents a method from being overridden in subclasses.
- What does JVM stand for?
Options:
- A) Java Virtual Machine
- B) Java Variable Method
- C) JRE Virtual Memory
- D) Just Virtual Machine
Answer: A) Java Virtual Machine
Explanation: JVM is the runtime engine that executes Java bytecode.
- Which collection class is synchronized by default?
Options:
- A) ArrayList
- B) HashSet
- C) Vector
- D) LinkedList
Answer: C) Vector
Explanation: Vector is thread-safe and synchronized, unlike other collections.
- What is the default value of a boolean in Java?
Options:
- A) true
- B) false
- C) null
- D) 0
Answer: B) false
Explanation: Uninitialized boolean variables default to false.
Practicing Java MCQ questions and answers helps reinforce key concepts. Have more questions or need clarification? Drop them in the comments below!