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Thinking in Java
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Standard Java exceptions

The Java class Throwable describes anything that can be thrown as an exception. There are two general types of Throwable objects (“types of” = “inherited from”). Error represents compile-time and system errors that you don’t worry about catching (except in special cases). Exception is the basic type that can be thrown from any of the standard Java library class methods and from your methods and run-time accidents. So the Java programmer’s base type of interest is usually Exception.

The best way to get an overview of the exceptions is to browse the HTML Java documentation that you can download from It’s worth doing this once just to get a feel for the various exceptions, but you’ll soon see that there isn’t anything special between one exception and the next except for the name. Also, the number of exceptions in Java keeps expanding; basically, it’s pointless to print them in a book. Any new library you get from a third-party vendor will probably have its own exceptions as well. The important thing to understand is the concept and what you should do with the exceptions.

The basic idea is that the name of the exception represents the problem that occurred, and the exception name is intended to be relatively self-explanatory. The exceptions are not all defined in java.lang; some are created to support other libraries such as util, net, and io, which you can see from their full class names or what they are inherited from. For example, all I/O exceptions are inherited from
Thinking in Java
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   Reproduced courtesy of Bruce Eckel, MindView, Inc. Design by Interspire