OOP Revision (Topic 6,7,8)

What does polymorphism mean?

• Having many forms

• A method of data encapsulation

• A way to create objects

• A type of inheritance

What is an abstract class?

• A class that contains only static methods

• A class that can be instantiated

• A class that has no methods

• A class that cannot be instantiated

What is the purpose of an abstract class?

• To create instances directly

• To provide a template for subclasses

• To store data only

• To implement all methods

What is method overriding?

• Defining a method in a subclass with the same name as in the superclass

• Changing the return type of a method

• Using multiple methods in a class

• Creating a new method in the superclass

What is a concrete class?

• A class that is used for inheritance only

• A class that only contains abstract methods

• A class that cannot have methods

• A class that can be instantiated

What does the 'instanceof' operator do?

• Checks the type of an object

• Creates a new instance of a class

• Overrides a method

• Declares a new class

What is the main advantage of polymorphism?

• Easier to modify and extend programs

• Faster execution of code

• More memory usage

• Less code to write

What must a non-abstract child class do?

• Have no methods at all

• Declare its own abstract methods

• Implement all abstract methods from the abstract class

• Inherit from multiple classes

What happens when you try to instantiate an abstract class?

• An error occurs

• It creates an instance

• It runs without any issues

• It creates a subclass

What is required for a method to be declared abstract?

• It must be private

• It must be static

• It must not have a body

• It must have a return type