SCJP 1.6版考題 038

1. class One{
2.   public One foo(){return this;}
3. }
4. class Two extends One{
5.   public One foo(){return this;}
6. }
7. class Three extends Two{
8.   //insert method here
9. }

Which two methods, inserted individually, correctly complete  the Three class? (Choose two.)
  A. public void foo(){} 
  B. public int foo(){return 3;}
  C. public Two foo(){return this;}
  D. public One foo(){return this;}
  E. public Object foo(){return this;}

解答

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Ans: C D

解說:

overriding  

比較要注意的是C為何可以，是因為Two is One(繼承關係)