SCJP Sun Certified Java Programmer MCQ 3

Question 1

Which interface must be implemented by a class to allow its objects to be sorted using Collections.sort()?

Accepted Answer

Comparable

Answer

A class must implement Comparable and override compareTo() to allow natural ordering via Collections.sort().

Question 2

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

Accepted Answer

Excludes a variable from serialization

Answer

A transient variable is skipped during object serialization and deserialization.

Question 3

Which of the following is true about Java interfaces prior to Java 8?

Accepted Answer

All methods in an interface are implicitly public and abstract

Answer

Before Java 8, all methods in an interface were implicitly public and abstract with no method body.

Question 4

What is the result of casting a double value 9.99 to int in Java?

Accepted Answer

9

Answer

Casting double to int truncates (not rounds) the fractional part, so 9.99 becomes 9.

Question 5

In Java, which exception type must be declared in a method's throws clause or handled with try-catch?

Accepted Answer

Checked exception

Answer

Checked exceptions (subclasses of Exception but not RuntimeException) must be declared or handled explicitly.

SCJP - Sun Certified Java Programmer Practice Test