type casting

[Akshay Rawal]

according to me type casting occurs only between classes which shares relation ship like IS-A ..but in below example though interface and class are not related then to it is not giving error

interface R{}

class P {}

class T extends P implements R {
//INSERT CODE HERE
}

if we insert R var = (R)new P(); it is not giving error..R and P are not related they are sharing relation with T

[hamada yam]

The cast is ok because you are testing for non-final class and at runtime some derived class of P may implement the interface R .
for e.g.

P p = new T();
R r = (R) p;

but if you declared your class P as final like

final class P {}
R r = (R) new P(); //compilation error

So in a nutshell for final class the compiler is sure whether the class implements interface or not but for non-final class compiler cannot be sure and that's why cast is allowed.

[Akshay Rawal]

ok...if final there's a compilation error...thanks for explanation