Java Programming for Complete Beginners - Java 16 - Step 19 - Java Interface Versus Abstract Class - a Comparison

The video tutorial explains the differences between abstract classes and interfaces. It highlights that while their syntax may appear similar, they serve different purposes. Interfaces are used to define communication patterns between systems, while abstract classes provide a high-level structure for subclasses. The tutorial also covers syntactical differences, such as visibility of methods and variable usage. It concludes by discussing how a class can implement multiple interfaces but cannot extend multiple abstract classes.

What is the primary reason for using an interface?

• To establish communication between systems or components

• To allow multiple inheritance

• To provide a high-level structure for subclasses

• To define private methods

What is the main purpose of an abstract class?

• To ensure all methods are public

• To allow multiple inheritance

• To define a communication pattern

• To provide a high-level structure and leave implementation to subclasses

Which of the following is true about methods in an interface?

• They can have a concrete implementation

• They are always public

• They can be private

• They can be protected

What is a key difference between abstract classes and interfaces regarding variables?

• Interfaces can have variables with changing values

• Abstract classes cannot have variables

• Variables in interfaces are constants

• Abstract classes can only have constant variables

Which statement is true about implementing interfaces and extending abstract classes?

• A class can extend multiple abstract classes but cannot implement multiple interfaces

• A class can implement multiple interfaces but cannot extend multiple abstract classes

• A class can both implement multiple interfaces and extend multiple abstract classes

• A class can neither implement multiple interfaces nor extend multiple abstract classes