Sams Teach Yourself Java 2 in 21 Days, Second Edition

Creating and Throwing Your Own Exceptions

There are two sides to every exception: the side that throws the exception and the side that catches it. An exception can be tossed around a number of times to a number of methods before it's caught, but eventually it will be caught and dealt with.

Who does the actual throwing? Where do exceptions come from? Many exceptions are thrown by the Java runtime or by methods inside the Java classes themselves. You can also throw any of the standard exceptions that the Java class libraries define, or you can create and throw your own exceptions. This section describes all these things.

Throwing Exceptions

Declaring that your method throws an exception is useful only to your method's users and to the Java compiler, ...