多态例子
一）相关类
class?A?...{
?????????public?String?show(D?obj)...{
????????????????return?("A?and?D");
?????????}??????????public?String?show(A?obj)...{????????????????return?("A?and?A");?????????}?
}?class?B?extends?A...{?????????public?String?show(B?obj)...{????????????????return?("B?and?B");?????????}?????????public?String?show(A?obj)...{????????????????return?("B?and?A");?????????}?}class?C?extends?B...{}?class?D?extends?B...{}?（二）问题：以下输出结果是什么？
????????A?a1?=?new?A();????????A?a2?=?new?B();????????B?b?=?new?B();????????C?c?=?new?C();?????????D?d?=?new?D();?????????System.out.println(a1.show(b));?? ①????????System.out.println(a1.show(c));?? ②????????System.out.println(a1.show(d));?? ③????????System.out.println(a2.show(b));?? ④????????System.out.println(a2.show(c));?? ⑤????????System.out.println(a2.show(d));?? ⑥????????System.out.println(b.show(b));???? ⑦????????System.out.println(b.show(c));?????⑧????????System.out.println(b.show(d));???? ⑨????（三）答案
????????????? ①?? A?and A
????????????? ②?? A and A
????????????? ③?? A and D
??????????????④?? B and A
????????????? ⑤?? B and A
????????????? ⑥?? A and D
????????????? ⑦?? B and B
????????????? ⑧?? B and B
????????????? ⑨?? A and D
?
转摘http://blog.csdn.net/thinkGhoster/article/details/2307001
