Android Programming for Beginners

Arrays and ArrayLists are polymorphic

We already know that we can put objects into arrays and ArrayList. But being polymorphic means that they can handle objects of multiple different types as long as they have a common parent type, all within the same array or ArrayList.

In Chapter 9, Object-Oriented Programming, you learned that polymorphism roughly means different forms. But what does it mean to us in the context of arrays and ArrayList?

Boiled down to its simplest, any subclass can be used as part of the code that uses the super class.

For example, if we have an array of Animals, we could put any object that is a type, that is a subclass of Animal in the Animal array, perhaps, Cats and Dogs.

This means that we can write code that is simpler and ...