interface Car{ } class Sports implements Car{ public void speedup(){ System.out.println("speeeeeeed up!"); } } class Shitty implements Car{ public void shit(){ System.out.println("shiiiiiit!"); } } public class MyClass { public static void main(String args[]) { Car c = new Sports(); boolean check = c instanceof Sports; System.out.println(check); // true c.speedup(); //Error ((Sports)c).speedup()..