SCJP - 23 - Given the following,

Which, inserted at line 9, will compile? (Choose all that apply.)
A. x2.do2();
B. (Y)x2.do2();
C. ((Y)x2).do2();
D. None of the above statements will compile.

Answer:

C is correct. Before you can invoke Y’s do2 method you have to cast x2 to be of type
Y. Statement B looks like a proper cast but without the second set of parentheses, the
compiler thinks it’s an incomplete statement.

A, B and D are incorrect based on the preceding.
(Objective 5.2)
==

class X { void do1() { } }
class Y extends X { void do2() { } }

class Chrome {
public static void main(String [] args) {
X x1 = new X();
X x2 = new Y();
Y y1 = new Y();
// insert code here
}
}