RuntimeException属于编程错误, 将被自动捕获, 不用自己写try, catch. 当然想捕获也可以, 但是没有这个必要, 如果是大程序也不可能做到.
看Thinking in java中的一段:
a RuntimeException represents a programming error:
An error you cannot anticipate. For example, a null reference that is outside of your control.
An error that you, as a programmer, should have checked for in your code (such as ArrayIndexOutOfBoundsException where you should have paid attention to the size of the array).