Question

Is it meaningful to declare a method to throw an exception
and a subclass of this exception,
e.g. IOException and FileNotFoundException?

I guess that it is used in order to handle both exceptions by a caller method differently.
However, is it possible to handle both exceptions if the method throws only the most generic i.e IOException?

Answer 1

However, is it possible to handle both exceptions if the method throws only the most generic i.e IOException?

Absolutely. You can still catch them separately:

try {
  methodThrowingIOException();
} catch (FileNotFoundException e) {
  doSomething();
} catch (IOException e) {
  doSomethingElse();
}

So it makes no difference to what the caller can do if the method declares both – it’s redundant. However, it can emphasize exceptions that you might want to consider. This could be done better in Javadoc than just the throws declaration.