java - 在空对象上抛出新的 NullPointerException VS 调用方法

Question

我想测试我的应用程序并检查它是否正确处理 NullPointerExceptions。

我有两个想法如何做到这一点：

throw new NullPointerException();

和：

((Object) null).hashCode();

它们都产生相同的堆栈跟踪。

第二个对我来说“更真实”，因为这是在我的真实代码中会发生的事情。

这两种说法有区别吗？我应该使用哪个？

Answer 1

Use directly

throw new NullPointerException();

Because,JRE throws NullPointerException when

• Calling the instance method of a null object.

• Accessing or modifying the field of a null object.

• Taking the length of null as if it were an array.

• Accessing or modifying the slots of null as if it were an array.

• Throwing null as if it were a Throwable value.

When you do this

((Object) null).hashCode();

You met the first condition and JRE throws the NPE.

Finally You are increasing one more step. That's it. No Difference.

Answer 2

利用

throw new NullPointerException();

因为您想测试您的应用程序NullPointerException是否正确处理 a 。

Answer 3

如文档所述，这两行代码都会引发相同的异常。除非您想测试 JRE / Java（这完全没有必要），否则就测试策略而言，这两行之间没有区别。