Quiz - Java Intermediate

1. Which of these is not a Java access modifier?

a. public

b. private

c. protected

d. internal

Correct Answer: internal
Explanation: Java does not have an "internal" access modifier.

2. Which interface must be implemented to allow an object to be cloned?

a. Serializable

b. Cloneable

c. Comparable

d. Runnable

Correct Answer: Cloneable
Explanation: Implementing the Cloneable interface allows the use of Object.clone().

3. Which of these is used for thread synchronization?

a. synchronized

b. volatile

c. transient

d. static

Correct Answer: synchronized
Explanation: The synchronized keyword ensures that only one thread can access a block/method at a time.

4. Which collection allows duplicate elements?

a. Set

b. List

c. Map

d. TreeSet

Correct Answer: List
Explanation: List allows duplicate elements; Set does not.

5. What is the size of int in Java?

a. 8 bits

b. 16 bits

c. 32 bits

d. 64 bits

Correct Answer: 32 bits
Explanation: In Java, an int is a 32-bit signed integer.

6. Which of these is not a Java keyword?

a. assert

b. enum

c. include

d. transient

Correct Answer: include
Explanation: "include" is not a Java keyword; it is used in C/C++.

7. Which method is used to start a thread?

a. run()

b. begin()

c. start()

d. execute()

Correct Answer: start()
Explanation: start() method is used to begin execution of a thread.

8. What is the default value of a boolean variable?

a. true

b. false

c. 0

d. null

Correct Answer: false
Explanation: The default value of a boolean in Java is false.

9. Which package contains the Random class?

a. java.io

b. java.util

c. java.lang

d. java.net

Correct Answer: java.util
Explanation: Random class is part of java.util package.

10. Which of the following is a marker interface?

a. Runnable

b. Serializable

c. Comparable

d. Callable

Correct Answer: Serializable
Explanation: A marker interface has no methods; Serializable is one example.

11. What is the output of 5/2 in Java?

a. 2

b. 2.5

c. 0

d. Exception

Correct Answer: 2
Explanation: Integer division truncates the decimal part in Java.

12. Which class is the superclass of all wrapper classes?

Java Intermediate Quiz