The set of checked exceptions is a subset of exceptions in java. Whenever you write code which can potentially throw one of these exceptions, you have to explicitly enclose that code in a try block and catch the checked exception. Or your method must explicitly declare it using a throws clause. Good question. This is an important concept in java.
Hi Anil, The JLS calls any exception that derives from the class Error or the class RuntimeException an unchecked exception.All other exceptions r called checked exceptions. It is the checked exceptions that r the ones u should deal with either by handling them or declaring in throws clause that they r not handled. Unchecked exceptions r either beyond ur control(Error) or result from conditions that u should not have allowed in the first place while programming(i.e., they r user mistakes while programming)(RuntimeException). Unchecked Exceptions r called so because the compiler does not check to see if a method handles them, or throws them.