QUESTION 22

QUESTION 22 
Given: 
 
abstract class A {
     abstract void a1(); 
 
     void a2() 
		{     }
} 
 
class B extends A {
     void a1() {     } 
     void a2() {     }
} 
 
class C extends B {
     void c1() {     }
} 
 
And: 
 
A x = new B();  
C y = new C();  
A z = new C(); 
 
What are four valid examples of polymorphic method calls? (Choose four.) 
 
A. x.a2(); 
B. z.a2(); 
C. z.c1(); 
D. z.a1(); 
E. y.c1(); 
F. x.a1(); 
Solution : ABDF

---

plus imformation 

C. z.c1(); // Won't compile. Method isn't defined in A

E. y.c1(); // Not polymorphic. Method is defined in declared class C.