class Animal {

    void eat() {

        System.out.println("Animal is eating");

    }

}

​

class Dog extends Animal {

    void bark() {

        System.out.println("Dog is barking");

    }

}

​

public class Example {

    public static void main(String[] args) {

        Animal myAnimal = new Dog();

        // Downcasting requires explicit casting and may throw a ClassCastException

        if (myAnimal instanceof Dog) {

            Dog myDog = (Dog) myAnimal;

            myDog.eat(); // Accessing the base class method

            myDog.bark(); // Accessing the derived class method

        }

    }

}

// reference primitive, and its type

SportsCar sc = new SportsCar();

Car c = sc;         // upcasting is implicit, this is OK!

sc.race();          // sc type is SportsCar, this is OK!

c.race();           // c type is Car, will NOT compile!

​

// Upcasting is implicit

Car myCar = new SportsCar();    // upcasting

Car myCar = sc;                 // upcasting is implicit

Car myCar = (Car) sc;       // (Car) is not necessary

​

// Downcasting is explicit

// potential ClassCastingException

// b/c Java will not always be able to determine that you've specified the right types at compile time

// So if you make a mistake you may encounter a run time error - hence Generics. 

SportsCar mySportsCar = (SportsCar) myCar;  // potential ClassCastingException

((SportsCar) c).race();     // downcasting to allow specialized subclass methods