SCJP Sun Certified Java Programmer MCQ 5

Question 1

Which operator is used to check if an object is an instance of a particular class or interface in Java?

Accepted Answer

instanceof

Answer

The 'instanceof' operator returns true if the object is an instance of the specified type.

Question 2

What is the purpose of the 'volatile' keyword in Java?

Accepted Answer

Ensures a variable is read from and written to main memory directly, not cached

Answer

The volatile keyword ensures all threads see the most up-to-date value by bypassing CPU caching.

Question 3

Which of the following correctly initializes a char variable in Java?

Accepted Answer

char c = 'A';

Answer

A char literal is enclosed in single quotes; double quotes are for String literals.

Question 4

What is the output of:
int x = 5;
System.out.println(x++);

Accepted Answer

5

Answer

The post-increment operator returns the current value (5) before incrementing x to 6.

Question 5

Which of the following is true about constructors in Java?

Accepted Answer

Constructors must have the same name as the class

Answer

A constructor must exactly match the class name and has no return type declaration, not even void.

SCJP - Sun Certified Java Programmer Practice Test