What is a Class?

A class is a blueprint (a design plan)

- Fields (Instance Variables)
- Constructors

- Methods (Functions)

What is Inheritance?

- What do classes have
in common?

- Abstract out those features

- Override or extend methods that don't work.

Is A? versus Has A?

- Is A? Helps you decide if a class should extend another.
  - Is A "Dog" an "Animal"?

  - Is A "Dog" a "Cat"?

- Has A? Helps you decide if something is a field.

  - Dog Has A height.

When to use Inheritance?

- When the subclass Is A superclass: "Dog Is An Animal"

- When a subclass need most of the methods in a superclass.

  - Almost every method in Animal is used in Dog.

- Don't: Use inheritance just to reuse code, or they don't have
  an Is A relationship.

Back to Inheritance?

- Fields and Methods are already defined
  when you extend the super class.
- You define only the changes.

Why we use Inheritance?

- Avoid duplicate code.

- Changes to superclass code is instantly reflected in subclasses.

- User knows that all subclasses have all of the methods of the superclass.

Types of Inheritance?