Here is the answer.
If a checked exception may be thrown within the body of a method, the method must either catch the exception or declare it in its throws clause.
This rule is actually for handling the exceptions: that is there are two ways by which we can handle the exception :
1: either you use the try catch statement and enclose the appropriate code in the try catch block this is called as the catch or the handle rule.
2: you can also use the throw and throws statement instead of using the try catch block i.e you should specify the exceptions that your method is capable of throwing(only checked).