H.5. Java Exception Hierarchy

All Java exception classes inherit directly or indirectly from class Exception, forming an inheritance hierarchy. You can extend this hierarchy with your own exception classes.

Figure H.3 shows a small portion of the inheritance hierarchy for class Throwable (a subclass of Object), which is the superclass of class Exception. Only Throwable objects can be used with the exception-handling mechanism. Class Throwable has two subclasses: Exception and Error. Class Exception and its subclasses—for instance, RuntimeException (package java.lang) and IOException (package java.io)—represent exceptional situations that can occur in a Java program and that can be caught by the application. Class Error and its subclasses represent abnormal situations that happen in the JVM. Most Errors happen infrequently and should not be caught by applications—it’s usually not possible for applications to recover from Errors.