Java, A Beginner's Guide, 5th Edition, 5th Edition

The Exception Hierarchy

In Java, all exceptions are represented by classes. All exception classes are derived from a class called Throwable. Thus, when an exception occurs in a program, an object of some type of exception class is generated. There are two direct subclasses of Throwable: Exception and Error. Exceptions of type Error are related to errors that occur in the Java virtual machine itself, and not in your program. These types of exceptions are beyond your control, and your program will not usually deal with them. Thus, these types of exceptions are not described here.

Errors that result from program activity are represented by subclasses of Exception. For example, divide-by-zero, array boundary, and file errors fall into this category. ...