Java, a robust and versatile programming language, is widely used in various domains from web development to mobile applications. For those preparing for Java interviews, certifications, or exams, mastering Java MCQ questions and answers can be a critical step. This article presents a curated selection of Java MCQs along with their answers to help you test and enhance your Java knowledge.

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

A) true

B) false

C) null

D) 0

Answer: B) false

Explanation: In Java, the default value of a boolean variable is false. This is part of Java’s initialization rules where instance variables are automatically initialized to their default values if not explicitly initialized.

2. Which of the following is not a valid keyword in Java?

A) static

B) synchronized

C) void

D) private

E) integer

Answer: E) integer

Explanation: integer is not a keyword in Java. The correct type for integers in Java is int. The other options, static, synchronized, void, and private, are all valid Java keywords.

3. What will be the output of the following code snippet?

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int x = 10;

int y = 20;

System.out.println(x + y);

A) 10

B) 20

C) 30

D) Error

Answer: C) 30

Explanation: The code snippet simply adds two integers, x and y, and prints the result. The sum of 10 and 20 is 30, so that is the output.

4. Which method is used to start the execution of a Java program?

A) run()

B) main()

C) execute()

D) start()

Answer: B) main()

Explanation: The main() method is the entry point of any Java application. It is where the Java Virtual Machine (JVM) starts execution of a program.

5. What does JVM stand for?

A) Java Virtual Machine

B) Java Variable Machine

C) Java Verified Machine

D) Java Virtual Method

Answer: A) Java Virtual Machine

Explanation: JVM stands for Java Virtual Machine. It is responsible for executing Java bytecode and providing a runtime environment for Java applications.

6. What is the purpose of the super keyword in Java?

A) To access superclass methods

B) To create a new instance of a superclass

C) To inherit properties from a superclass

D) To finalize a class

Answer: A) To access superclass methods

Explanation: The super keyword in Java is used to refer to the immediate parent class object. It is often used to access superclass methods and constructors.

7. Which of the following is a valid declaration of a char variable in Java?

A) char ch = "A";

B) char ch = 'A';

C) char ch = A;

D) char ch = "A"; // Error

Answer: B) char ch = 'A';

Explanation: In Java, a char variable is declared using single quotes ('A'). Double quotes are used for String literals, not for char literals.

8. How do you declare an array in Java?

A) int[] arr;

B) int arr[];

C) Both A and B

D) None of the above

Answer: C) Both A and B

Explanation: Both int[] arr; and int arr[]; are valid ways to declare an array in Java. The first syntax is preferred as it emphasizes that arr is an array of int.

9. What will be the output of the following code?

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int x = 5;

System.out.println(x++);

A) 5

B) 6

C) Error

D) 0

Answer: A) 5

Explanation: The x++ statement is a post-increment operation. This means it will print the value of x before incrementing it. Thus, 5 will be printed, and x will be incremented to 6 after the statement.

10. What is the correct way to handle exceptions in Java?

A) using try-catch block

B) using throws keyword

C) using throw keyword

D) using error handling functions

Answer: A) using try-catch block

Explanation: In Java, exceptions are typically handled using a try-catch block. This allows you to catch exceptions that may occur and handle them appropriately.

Conclusion

Preparing for Java MCQ questions and answers can significantly enhance your understanding and application of Java concepts. By familiarizing yourself with these types of questions and their answers, you can better prepare for exams, interviews, and practical applications. Keep practicing and exploring more questions to deepen your knowledge and improve your Java skills.