Subclasses

Subclasses model the inheritance of attributes.

Let's start with a base Animal class.

Like before, creating an instance.

We're going to make Cat extend the properties of Animal.

It can be thought of as copying over the variables and methods from Animal. Notably, the Animal constructor gets renamed to super. The cyan text doesn't actually exist in the code.

We can create an instance of this Cat class. speak is available since it is inherited from Animal.

Note that every Cat is also an Animal. They have the same properties and methods.

For a more complex example, let's also include an extra field and method in a new version of Cat.

We can now create this new Cat, giving it a whiskers count. speak can be used based on the Animal superclass, and age was added for the Cat class.

Like before, every Cat is also an Animal. This relationship is always true for subclasses. However, in this case, it also includes some extra things like whiskers and age.