In class-based programming, downcasting or type refinement is the act of casting a reference of a base class to one of its derived classes. In many programming languages, it is possible to check through type introspection to determine whether the type of the referenced object is indeed the one being cast to or a derived type of it, and thus issue an error if it is not the case. In other words, when a variable of the base class (parent class) has a value of the derived class (child class), downcasting is possible. ==Example== In Java: public class Fruit