class A {}
class B extends A {}
class C extends A {}
class D extends C {}

class TrueOrFalse {
    public static void main(String[] args) {
        A a = new A();
        B b = new B();
        C c = new C();
        D d = new D();
        A e = new D();
        A f = new B();

        System.out.println("a) " + (b instanceof A));
        System.out.println("b) " + (c instanceof D));
        System.out.println("c) " + (d instanceof A));
        System.out.println("d) " + (e instanceof C));
        System.out.println("e) " + (f instanceof C));

        //Tilfelle 1
        B ab = (B) a;   //Ikke lovlig

        //Tilfelle 2
        if( e instanceof B ){   //er false, blir derfor ingen feilmelding
                                //ettersom at neste linje ikke kjøres
            B eb = (B) e;   //Ikke lovlig, men kjøres ikke. Ikke noe problem
        }

        //Tilfelle 3
        D ed = (D) e;   //Lovlig

        //Tilfelle 4
        if( e instanceof D ){
            
            D edd = (D) e;  //Lovlig
        }

        //Tilfelle 5
        B fb = (B) f;   //Lovlig

        //Tilfelle 6
        C ec = (C) e;   //Lovlig

    }
}