Hands-On Design Patterns with Java

Polymorphism

Polymorphism is not a word that non-OOP programmers are likely familiar with. The term polymorphism is generally defined as appearing in multiple forms. In OOP, polymorphism states that different types of objects can be accessed via a common interface. This can be achieved by writing overloaded constructors and methods and is covered later in this chapter. Polymorphism can also be achieved by having subclasses override superclass methods.

Let's take a simple look at this using Java code:

1. First, we create a Vehicle class that, by default, extends Java's Object class.
2. Next, we create a TwoWheeled class that extends the Vehicle class.
3. Then, we create a Bicycle class that extends the TwoWheeled class.

4. Lastly, we create a Driver ...