java Exception 类

http://www.blogjava.net/fhtdy2004/archive/2009/06/18/283133.html

http://onjava.com/pub/a/onjava/2003/11/19/exceptions.html

Types of Exceptions in Java

Java defines two kinds of exceptions:

• Checked exceptions: Exceptions that inherit from the Exception class are checked exceptions. Client code has to handle the checked exceptions thrown by the API, either in acatch clause or by forwarding it outward with thethrows clause.

• Unchecked exceptions: RuntimeException also extends fromException. However, all of the exceptions that inherit fromRuntimeException get special treatment. There is no requirement for the client code to deal with them, and hence they are called unchecked exceptions.

By way of example, Figure 1 shows the hierarchy for NullPointerException.

Figure 1. Sample exception hierarchy