Java: Upcasting and Dynamic Dispatch

Upcasting allows treating a subclass object as an instance of its superclass.

Upcasting is useful when you want to handle different subclasses through a common superclass reference. It helps in achieving polymorphism. For instance, in an e-commerce system, you can upcast a `Book` object to a `Product` reference to process it in a generic inventory system without caring about its specific type.