SCJP 1.6版考題 034

Which four statements are true? (Choose four.)
   A. Has-a relationships should never be encapsulated.
   B. Has-a relationships should be implemented using inheritance.
   C. Has-a relationships can be implemented using instance variables.
   D. Is-a relationships can be implemented using the extends keyword.
   E. Is-a relationships can be implemented using the implements keyword.
   F. The relationship between Movie and Actress is an example of an is-a relationship.
   G. An array or a collection can be used to implement a one-to-many has-a relationship. 

解答

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Ans: C D E G

解說:

那四個敘述是正確的？
  Has-a 關係應該永遠不能被封裝
  Has-a 關係應該以繼承的方式實作
  Has-a 關係可以用物件變數的方式被實現出來
  Is-a關係可用extends關鍵字實現出來
  Is-a關係可用implements關鍵字實現出來
電影和女演員間的關係是一個Is-a關係的例子
一個陣列或一個集合可以被用來實作一對多的has-a關係