Exceptions and Assertions - The Java Programming Language - page 423

This example code is prepared to handle one of the exceptions re-
placeValue throws:
Object value = new Integer(8);
try {
attributedObj.replaceValue("Age", value);
} catch (NoSuchAttributeException e) {
// shouldn't happen, but recover if it does
Attr attr = new Attr(e.attrName, value);
attributedObj.add(attr);
}
The try sets up a statement (which must be a block) that does
something that is normally expected to succeed. If everything succeeds,
the block is finished. If any exception is thrown during execution of the
code in the try block, either directly via a throw or indirectly by a meth-
od invoked inside it, execution of the code inside the try stops, and the
attached catch clause is examined to see whether it wants to catch the
exception that was thrown.
A catch clause is somewhat like an embedded method that has one para-
meter namely, the exception to be caught. As with method parameters,
the exception "parameter" can be declared final , or can have annota-
tions applied. Inside a catch clause, you can attempt to recover from the
exception, or you can clean up and rethrow the exception so that any
code calling yours also has a chance to catch it. Or a catch can do what it
needs to and then fall out the bottom, in which case control flows to the
statement after the try statement (after executing the finally clause, if
there is one).
A general catch clauseone that catches exceptions of type Exception , for
exampleis usually a poor implementation choice since it will catch any
exception, not just the specific one you are interested in. Had we used
such a clause in our code, it could have ended up handling, for example,
a ClassCastException as if it were a missing attribute problem.