Chapter 9

Question 1

Should io functions use try catch

Answer 1

Yes

Question 2

How to define abstract class in JAVA

Answer 2

by using abstract keyword

Question 3

How to define a method abstract in JAVA

Answer 3

by using abstract keyword

Question 4

Does interface a pure abstract class

Answer 4

Yes

Question 5

What is pure abstract class / interface

Answer 5

In there, there is no implementation, only method signatures

Question 6

How to define an interface

Answer 6

By using interface keyword

Question 7

Who implement interface

Answer 7

classes

Question 8

If a class implementing interface does not provide definition of all methods, it will not compile. How could we compile it

Answer 8

By making it abstract

Question 9

Can class implement more than one interface

Answer 9

yes. multiple inheritance

Question 10

Can an interface inherit from another interface

Answer 10

Yes

Question 11

Can an object of interface instantiated

Answer 11

No

Question 12

What are abstract classes

Answer 12

Abstract classes are classes that contain one or more abstract methods. An abstract method is a method that is declared, but contains no implementation. Abstract classes may not be instantiated, and require subclasses to provide implementations for the abstract methods.