please explain this catch

- why do we put "input.next line" in one but not the other? what does it do?

- what is the point of the last catch (exception), what does it do? is it neccessary to use always?

} catch (IndexOutOfBoundsException ex) { System.err.println("Level [" + level + ") has 5 courses." + "You cannot add more courses to this level.."); } catch (InputMismatchException ex) { System.err.println("Input Mismatch Exception"); input.nextLine(): } catch (Exception ex) 1 System.err.println(ex.getMessage(): input.nextLine()