SCJP題庫第139題

Given a method that must ensure that its parameter is not null:

11. public void someMethod(Object value){

12.   //check for null value

...

20.   System.out.println(value.getClass());

21. }

What, inserted at line 12, is the appropriate way to handle a null value?

A. assert value == null;

B. assert value != null : "value is null";

C. if (value == null){

       throw new AssertionException("value is null");

 }

D. if (value == null){

       throw new IllegalArgumentException("value is null");

 }

 

Ans: D

 

解說:

value是公開的方法someMethod中的參數，此參數會由類別外部給予值，類別無法控制此值…

這種性質的參數測試不適合用asserttion(因assertion可以隨時關掉)