interface and abstract class

Abstract class can have

• Abstract methods

• Methods with code implementation

• Used to create objects

• Used to create subclasses

What is an abstract method?

• An abstract method is any method in an abstract class.

• An abstract method is a method which cannot be inherited.

• An abstract method is one without a body that is declared with the reserved word abstract.

• n abstract method is a method in the child class that overrids a parent method.

Can an abstract class define both abstract methods and non-abstract methods?

• No—it must have all one or the other.

• No—it must have all abstract methods.

• Yes—but the child classes do not inherit the abstract methods.

• Yes—the child classes inherit both.

Inheritance is used when the relationship between two classes is a(n) _______ relationship.

• "HAS-A"
• "PART-OF-A"
• "IS-A"
• inverse

Which of these class is super class of every class in Java?

• String class

• Object class

• ArrayList class

• Abstract class

Which of these keywords can be used to prevent inheritance of a class?

• super

• constant

• extends

• final

Which of these class relies upon its subclasses for complete implementation of its methods?

• Object class

• abstract class

• ArrayList class

• None of the mentioned

What will be the output of the following Java program?

• 2

• 0

• Compilation Error

• Runtime Error

Which of these keywords are used to define an abstract class?

• Abstract

• abstract

• abstract class

• abst

In order to restrict a variable of a class from inheriting to subclass, how variable should be declared?

• Protected

• Private

• Public

• Static