Java的异常处理是通过5个关键字来实现的：try，catch，throw，throws，finally。JB的在线帮助中对这几个关键字是这样解释的：

Throws:Lists the exceptions a method could throw.

Throw:Transfers control of the method to the exception handler.

Try：Opening exception-handling statement.

Catch：Captures the exception.

Finally：Runs its code before terminating the program.