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JBridge: Certification Question Of The Day |
| JBridge Home >> Certification Questions >> Today's Question | Last updated: Friday 2nd May 2003 |
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A browser sends a request containing no headers to a servlet. What is the result of executing the following method within the servlet?
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String s = request.getHeader("Date");
System.out.println(s);
}
A "null" is output to the resulting web page. B A DateHeaderException is thrown. C A date is printed on the returned web page. D The code never runs, as the servlet will not compile. E "null" is output to the console. Page down for the answer... The AnswerThe correct answer is E, "null" is output to the console. When the method getHeader(String headerName) receives a header name it doesn't recognize, it returns a null object. When System.out.println receives a null object reference as a parameter, it prints out the word "null". Nothing is output to the web page; for that to happen, the method would need to retrieve a Writer or OutputStream from the response. The OutputStream associated with System.out.println is the console (for the application server running the servlet). So A and C could not be correct. There is no such thing as a "DateHeaderException" - at least, not defined in javax.servlet or related packages - so B cannot be correct. Finally, the code compiles just fine. The red herring factor here is that if you're retrieving a date, should the returned value not be long? So returning the value to a String would give you an incompatible type error? It would be if the method called was request.getDateHeader() - which it isn't. So that rules out answer D. |
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