Factory method pattern
The fourth design pattern that you will learn now is the Factory method. This pattern deals with the creation of objects and particularly with delegating the creation of objects using sub-classes. The objects you want to create usually share a common characteristic; they are similar in nature or in type, or they are part of a hierarchy.
You use an interface with a distinct create method and then you provide concrete classes that implement this factory and construct objects of a particular sub-class. Then this factory interface can be used in places where you have hardcoded types in parameters or variables.
A factory object is an abstraction that is responsible for creating objects. The way that it creates them though is the key differentiator. When you have multiple types of objects that either inherit from a similar class or have a similar role, then you may find that passing each type as a parameter is cumbersome. You will have to create all those different...