第51題

1. public interface A{
2. public void doSomething(String thing);
3. }
1. public class AImpl implements A{
2. public void doSomething(String msg){}
3. }
1. public class B{
2. public A doit(){
3. //more code here
4. }
5.
6. public String execute(){
7. //more code here
8. }
9. }
1. public class C extends B{
2. public AImpl doit(){
3. //more code here
4. }
5.
6. public Object execute(){
7. //more code here
8. }
9. }
Which statement is true about the classes and interfaces?
A. Compilation will succeed for all classes and interfaces.
B. Compilation of class C will fail because of an error in line 2.
C. Compilation of class C will fail because of an error in line 6.
D. Compilation of class AImpl will fail because of an error in line 2.
答案：C
參考：6-5 繼承、7-6 介面
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6. public Object execute(){ 試圖要實做
6. public String execute(){ 但是回傳型別不同...