Why should we write custom exception classes in Java

Question

What is the purpose of writing custom exception classes when mostly what it does is same. For eg, NullPointerException:

class NullPointerException extends Ru         


        

Answer 1

It is basically to Handle different Exception in different ways. Say, you might want to do some different operation on ArrayIndexOutOfBoundsException than a NumberFormatException.

or more clearly

}catch (ArrayIndexOutOfBoundsException ex){
//operation 1
}catch (NumberFormatException ex){
//operation 2
}