Learn Java from Scratch - A Beginner's Guide - Step 20 - Java Interface Flyable and Abstract Class Animal - an Exercise

The video tutorial explains the differences between interfaces and abstract classes, using examples of a Flyable interface and an Animal abstract class. It includes exercises to implement these concepts with Bird and Aeroplane classes for interfaces, and Dog and Cat classes for abstract classes. The tutorial provides a solution for the interface exercise and encourages viewers to attempt the abstract class exercise independently. The video concludes with a brief mention of polymorphism as a future topic.

What is the primary purpose of an interface in programming?

• To provide a graphical user interface

• To store data in a structured format

• To manage memory allocation

• To define common actions that can be performed by different classes

Which method should be implemented by the Bird class in the Flyable interface?

• Fly

• Jump

• Swim

• Run

In the Flyable Runner class, what is the purpose of creating an array of Flyable objects?

• To display the names of all flying objects

• To calculate the total number of flying objects

• To sort the objects based on their flying speed

• To store different types of flying objects and invoke their fly methods

What is the output when the fly method is called on a Bird object?

• With fuel

• With wings

• With speed

• With feathers

What is the expected output when the fly method is called on an Airplane object?

• With passengers

• With fuel

• With speed

• With wings

What is the main characteristic of an abstract class?

• It cannot be extended by other classes

• It only contains static methods

• It can have both abstract and concrete methods

• It can be instantiated directly

Which method should be implemented by the Dog class in the Animal abstract class?

• Bark

• Swim

• Meow

• Fly