SCJP題庫第191題
Given:
11. //insert code here
12. private N min, max;
13. public N getMin() { return min; }
14. public N getMax() { return max; }
15. public void add(N added) {
16. if(min == null || added.doubleValue() < min.doubleValue())
17. min = added;
18. if(max == null || added.doubleValue() > max.doubleValue())
19. max = added;
20. }
21.}
Which two, inserted at line 11, will allow the code to compile? (Choose two.)
A. public class MinMax<?>{
B. public class MinMax<? extends Number>{
C. public class MinMax<N extends Object>{
D. public class MinMax<N extends Number>{
E. public class MinMax<? extends Object>{
F. public class MinMax<N extends Integer>{
Ans: DF
解說:
Number 是Integer, Short等包裝型別的父類別
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