Question

If I put a try/catch in a throws function, in case of an exception which one runs?

1. Does it do whatever in catch clause, throws an exception or both?

2. Adding some more details, what if the exception in the inner scope
   is inherited form the other or vice versa?

3. What does this function when post doesn’t include a parameter?

Example :

 public void doPost(HttpServletRequest req, HttpServletResponse resp) 
        throws ServletException{
        int number;
    try {
            number = Integer.parseInt(getParameter(req,"number"));
        } catch (Exception e) {
    number = 5;
        }
    }

where getParameter is a function in my BaseServlet class which extends HttpServlet:

protected String getParameter(HttpServletRequest req, String parameter)
    throws ServletException {
    String value = req.getParameter(parameter);
    if (isEmptyOrNull(value)) 
        throw new ServletException("Parameter " + parameter + " not found");

    return value.trim();
}

Answer 1

If you choose to both handle the exception (using try/catch) and duck the exception(using throws clause), compiler chooses to handle the exception.
In your case, it will catch the exception and assign 5 to number.

And a Suggestion:

its a bad practice to handle all exceptions inside a single catch block, i.e.,

catch(Exception e)

always catch most Specific exceptions.