Design Patterns and Best Practices in Java

The factory pattern

As discussed in the previous chapter, inheritance is one of the fundamental concepts in object-oriented programming. Along with subtyping polymorphism, it gives us the is/a relationship. A Car object can be handled as a Vehicle object. A Truck object can be handled as a Vehicle object too. On one hand, this kind of abstraction makes our code thinner, because the same piece of code can handle operations for both Car and Truck objects. On the other hand, it gives us the option to extend our code to new types of Vehicle objects by simply adding new classes such as Bike and Van without modifying it.

When we deal with such scenarios, one of the trickiest parts is the creation of objects. In object-oriented programming, each ...