SCJP Java OOP and Inheritance 2

Question 1

Which of the following correctly describes method overloading in Java?

Accepted Answer

Same method name, different parameter list in the same class

Answer

Method overloading requires the same method name but a different parameter list (number, type, or order) within the same class.

Question 2

What is the IS-A relationship in Java OOP?

Accepted Answer

Inheritance

Answer

The IS-A relationship is established through inheritance — a subclass IS-A type of its superclass.

Question 3

Which of the following is NOT a valid way to achieve polymorphism in Java?

Accepted Answer

Method overloading at runtime

Answer

Method overloading is resolved at compile time (static binding), so it does not contribute to runtime polymorphism.

Question 4

If class B extends class A and both define `toString()`, which `toString()` is called when `A obj = new B(); System.out.println(obj);`?

Accepted Answer

B's toString()

Answer

Because `toString()` is overridden in B and Java uses dynamic dispatch, B's `toString()` is invoked at runtime.

Question 5

Which Java feature allows a class to inherit behavior from multiple sources without multiple inheritance of classes?

Accepted Answer

Interfaces with default methods

Answer

Since Java 8, interfaces can have `default` methods, allowing a class to inherit behavior from multiple interfaces.

SCJP - Sun Certified Java Programmer Practice Test