Typing

ExampleCasting.JAVA

public class ExampleCasting {

    public static void main (String[] args) {

        Animal a1 = new Dog();
        Dog d1 = new Dog();
        a1 = d1;

        // Dog d2 = new Animal(); // compiler: incompatible types
        //  Dog d2 = (Dog) new Animal(); // runtime: ClassCastException

        Dog d3 = new Dog();
        Animal a3 = d3;
        Dog d4 = (Dog) a3;

        Animal a5 = new Dog();
        //Dog d5 = a5;   // compiler: incompatible types
        Dog d6 = (Dog) a5;

        Helicopter h = new Helicopter();
        // Animal a5 = (Animal) h;  // compiler: incompatible types


        // let's try with interfaces now...

        Inflatable i = new Balloon();
        i = new Balloon();

        //Balloon b = i; // compiler: incompatible types
        Balloon b = (Balloon) i;

        // PartyBalloon bb = (PartyBalloon) new Balloon();  // runtime: ClassCastException

        // PartyBalloon bb2 = i;  // compiler: incompatible types
        //PartyBalloon bb3 = (Balloon) i;  // compiler: incompatible types
        PartyBalloon bb4 = (PartyBalloon) i;

        i = new Pool();
        b = new Balloon();
        i = b;
    }
}

class Animal {
}

class Helicopter {
}

class Dog extends Animal {
}


interface Inflatable {
}

class Balloon implements Inflatable {
}

class PartyBalloon extends Balloon {
}

class Pool implements Inflatable {
}