问题:
1. class Alpha { void m1() {} }
2. class Beta extends Alpha { void m2() { } }
3. class Gamma extends Beta { }
4.
5. class GreekTest {
6. public static void main(String [] args) {
7. a Alpha [] a = {new Alpha(), new Beta(), new Gamma() };
8. for(Alpha a2 : a) {
9. a2.m1();
10. if (a2 instanceof Beta a2 instanceof Gamma)
11. //insert code here
12. }
13. }
14. }
哪一行代码插入到第11行,将编译但是会在运行时产生异常?()
A . a2.m2();
B . ((Beta)a2).m2();
C . ((Alpha)a2).m2();
D . ((Gamma)a2).m2();
1. class Alpha { void m1() {} }
2. class Beta extends Alpha { void m2() { } }
3. class Gamma extends Beta { }
4.
5. class GreekTest {
6. public static void main(String [] args) {
7. a Alpha [] a = {new Alpha(), new Beta(), new Gamma() };
8. for(Alpha a2 : a) {
9. a2.m1();
10. if (a2 instanceof Beta a2 instanceof Gamma)
11. //insert code here
12. }
13. }
14. }
哪一行代码插入到第11行,将编译但是会在运行时产生异常?()
● 参考解析
本题暂无解析