Introduction

Question 1

Define an exception that java makes for interfaces !

Answer 1

Java makes an exception when it comes to interfaces about multiple inheritance where an interface can implement multiple interfaces

Question 2

Define an interface !

Answer 2

an interface is an abstract data type that is defined in java with
the keyword interface

Question 3

What type of members can an interface contain ?

Answer 3

An interface can only contain public abstract methods, public static final variables and default methods

Question 4

How to declare an interface ?

Answer 4

In Java, an interface is defined with the interface keyword, analogous to the class keyword used when defining a class.

Question 5

How does a class implement an interface ?

Answer 5

A class implements an interface using the “implements” keyword

Question 6

Give the full syntax of declaring an interface and members of
the interface with showing which parts are required and which parts are assumed ?

Answer 6

when declaring an interface , the ‘abstract’ specifier is assumed and the ‘interface’ keyword is required.

When declaring a variable inside an interface, it is assumed to be public and static and final.

When declaring a method inside an interface, it is assumed to be abstract and public

Question 7

Give an example of a class implementing more than one interface !

Answer 7

public class Elephant implements WalksOnFourLegs, HasTrunk, Herbivore {
}

In the example, if any of the interfaces defined abstract methods, the concrete class Elephant would be required to implement those methods

Question 8

What does that imply ?

Answer 8

It does imply that the concrete class is required to implement all of the abstract methods defined in the implemented interfaces