JBridge: Certification Question Of The Day

Identify true statements about the following servlet code? (the line numbers are not part of the code) (1 correct answer)

11  RequestDispatcher rd = request.getRequestDispatcher("/InventoryServlet");
12  PrintWriter out = response.getWriter();
13  out.write("Inventory Report");
14  out.flush();
15  out.close();
16  rd.include(request, response);

The Answer

G is the correct answer.
Because the response output stream has been closed, the "include" at line 16 has no effect. So the output from "InventoryServlet" is not returned (answers B and C are wrong). The servlet compiles just fine, invalidating answer A.
No output occurs because of the runtime error, invalidating answers B and C.
Although output has been committed (in line 14 - out.flush()), it is OK still to invoke include() method on a RequestDispatcher. Had this been the forward() method here, then the IllegalStateException mentioned in answer D would have occurred.
There is no reason for line 16 not to execute; it just doesn't influence the output (answer E).
Finally, answer F is meant to make you think this is the root cause of the compilation error (or perhaps gives rise to a runtime error). The opposite of the truth is stated here. A RequestDispatcher returned from ServletContext does require "/" at the beginning of the parameter to getRequestDispatcher. However, the opposite of this is not true: a RequestDispatcher returned from the Request can legitimately have "/" (or not) at the beginnng of the parameter to getRequestDispatcher.