Thread: why should we declare checked exceptions?

Hi !My doubt is on checked,unchecked exceptions in java.
1)You know that if there is any possibility for checked exception to be thrown from a method and we do not have intention to handle the thrown exception then we have to declare that exception in method header.That means we have to write “throws EXCEPTION NAME” in method header.
2)But in case of unchecked exception, if there is any possibility for unchecked exception to be thrown from a method then we do not declare that exception in method header.. That means we do not write “throws EXCEPTION NAME” in method header .
3)Why should we declare the exception in method header in case of checked exceptions ? what benefits are we getting by declaring exception in method header?
4)Why do not we declare the exception in method header in case of unchecked exceptions?

in case of checked exceptions-it follows throw early catch later principal which is necessary for handling the exceptions.
in case of unchecked exceptions-we donot know the type of exception, they occur at runtime. so we cannot throw the unchecked exceptions.

The Exception which are checked by compiler for smooth execution of the program at runtime are called Checked Exception. In the case of Checked exception, compiler will check whether we are handling the exception if not then we will get the compiler error that means checked exceptions are subject to the Catch or Specify Requirement.

3)Why should we declare the exception in method header in case of checked exceptions ? what benefits are we getting by declaring exception in method header?

Checked exceptions must be caught somewhere within your application. If the function is not able to properly deal with the exception, it should not catch it, but has to let it propagate up the call stack to someone who does catch it. That's the reason for "throws Exception", to propagate the exception up the call stack instead of dealing with it right there.

4)Why do not we declare the exception in method header in case of unchecked exceptions?

It's mostly for programmer convenience. It would be horrible to have to try/catch everything that could possibly be null, for example. Unchecked exceptions get caught by the JVM and printed to System.err.