Java requires that each method must address every checked exception that can be thrown during its execution either by handling the exception within a try-catch block or by declaring that the exception can propagate out of the method (via the throws clause). Unfortunately, there are a few techniques that permit undeclared checked exceptions to be thrown at runtime. Such methods techniques foil the ability of caller methods to use the throws clause to determine the complete set of checked exceptions that could propagate from an invoked method. Consequently such techniques must not be used to throw undeclared checked exceptions.
...