Exception Handling - Java: A Beginner's Guide - page 423

As the output confirms, each catch statement responds only to its own type of exception.
In general, catch expressions are checked in the order in which they occur in a program.
Only a matching statement is executed. All other catch blocks are ignored.
Catching Subclass Exceptions
There is one important point about multiple catch statements that relates to subclasses. A
catch clause for a superclass will also match any of its subclasses. For example, since the
superclass of all exceptions is Throwable , to catch all possible exceptions, catch Throw-
able . If you want to catch exceptions of both a superclass type and a subclass type, put the
subclass first in the catch sequence. If you don't, then the superclass catch will also catch
all derived classes. This rule is self-enforcing because putting the superclass first causes
unreachable code to be created, since the subclass catch clause can never execute. In Java,
unreachable code is an error.
For example, consider the following program:
The output from the program is shown here: