SCJP 1.6版考題 063
出自 陳富國維基館
11. class ClassA{}
12. class ClassB extends ClassA{}
13. class ClassC extends ClassA{}
and:
21. ClassA p0 = new ClassA();
22. ClassB p1 = new ClassB();
23. ClassC p2 = new ClassC();
24. ClassA p3 = new ClassB();
25. ClassA p4 = new ClassC();
Which three are valid? (Choose three.)
A. p0 = p1;
B. p1 = p2,
C. p2 = p4;
D. p2 = (ClassC)p1;
E. p1 = (ClassB)p3;
F. p2 = (ClassC)p4;
解答
Ans: A E F
解說:
B和C是A的子類別 父類別的參考型態可以指向子類別態物件(因為子類別 is a 父類別)
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