Design issues, need advice.

[ddmeightball]

I am having problems with adding a servlet to a program that I have written previously. Its not the servlet that is throwing me for a loop, its when I need to check to see if the appointment I am adding to the list is the same time as another appointment in the list.

Here is what I want to do, just so you know.

Have the user enter the information for one appointment and add it to the list, if that time is available.

Show the results.

If the date/time is unavailable, redirect to an error JSP.

You will notice in my ApptServlet.java, I have commented out a few lines of code related to the checking to see if the date is taken or not.

			if(pl.isTaken(appt))
			{
				RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/Error.jsp");
				dispatcher.forward(request, response);
			}//end if
			else
			{
				List plist = pl.getPatientList();
				request.setAttribute("plist",plist);
				RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/Results.jsp");
				dispatcher.forward(request, response);
			}//end else

What I want to do is, in the ApptServlet.java if the date is taken, redirect to the Error.jsp. Else, set the patientList to the request object then redirect to the Results.jsp.

I am trying to use an If Else statement to sort this out. I am using a method called isTaken() that checks the date of the appointment object that I want to add to the list against the dates of the appointment objects already in the list.

The problem is I dont know how I should this in the following method. If the date is taken, I want to redirect to the error.jsp, but how would I do that.

	public void setAppointments(String n, int pID, boolean apptReason, int year, int month, int date, int hourOfDay, int minute)
	{
		//Create an new appointment object then add the appointment to the list
		Appointment appt = new Appointment(n, pID, apptReason, year, month, date, hourOfDay, minute);
		
		//check to see if the appointments date = the date of another appointment
		//Can I do something to foward the request dispatcher here if I extend HTTPServlet?
		if(pl.isTaken(appt))
		{
		//I want to redirect to the error.jsp
		}
		else
		{
			patientList.add(appt);
		}
	}

I have included my full code in a zip file.

[ComputerJy]

Mark your method to throw an Exception with the message "appt taken" for example and catch it in the main ServLet class.
if Exception caught and with the same body then redirect to the "error.jsp"

[ddmeightball]

Mark your method to throw an Exception with the message "appt taken" for example and catch it in the main ServLet class.
if Exception caught and with the same body then redirect to the "error.jsp"

Could you give me an example of what you mean? Do you mean to throw and exception i nmy PatientList.setAppointments(). What exception would I have to catch in my servlet?

[ddmeightball]

Isnt using exceptions like that really abusing exceptions and not the correct way to code? Arent Exceptions meant for exceptional conditions, not normal program flow?

[ddmeightball]

Ok, for the time being, I have commented out the sections related to checking to see if the appointment date is available.

I am trying to atleast get it to work first then worry about checking for availibility.

I am getting an error

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: Unable to compile class for JSP

Generated servlet error:
Syntax error, insert "}" to complete Block

Generated servlet error:
Syntax error on token "}", delete this token

Generated servlet error:
Syntax error, insert "}" to complete ClassBody


org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:84)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:328)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:409)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:288)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:267)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:255)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:563)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
business.ApptServlet.doGet(ApptServlet.java:64)
business.ApptServlet.doPost(ApptServlet.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


note The full stack trace of the root cause is available in the Apache Tomcat/5.5.12 logs.


--------------------------------------------------------------------------------

The only part that I can recognize is

business.ApptServlet.doGet(ApptServlet.java:64)
business.ApptServlet.doPost(ApptServlet.java:70)

So I went and looked at those two lines of my servlet and I cant see why I am getting an error with them.

Line 64

dispatcher.forward(request, response);

Line 70

doGet(request, response);

I have included an updated version of my code in a ZIP file in this post.

[ComputerJy]

in public void setAppointment(...) add this:

if(pl.isTaken(appt))
{
throw new ServletException("redirect to error");
}

Then Add throws ServletException to setAppointment(...) and to public PatientList(...)

On doGet(...) in ApptServlet class add the following:

try {
        pl = new PatientList(strName, patID, reason, year
                             , month, date, hour, minute) ;
      }
      catch (ServletException ex) {
        if (ex.getMessage().equals("redirect to error")) {
          getServletContext().getRequestDispatcher("/Error.jsp").include(
              request, response) ;
        }
      }

[ddmeightball]

Not that that wont work, but am I supposed to be using exceptions that way?

[ddmeightball]

Now, it is printing out the Information that you enter in the Assign2.jsp. But what good is an appointment program if you cant enter more than one correct?

Well, now I am trying to add sessions to my servlet and I am failing horribly it seems. It will still print out the information for the one person that you enter, but if you enter another patients information, it overwrites the previous one. I have been looking and cant find what I am doing wrong. I dont believe I am using sessions correctly. Any ideas?

[ComputerJy]

If you really need help contact me on any IM on my public profile

[ddmeightball]

Ok, I have gotten a little further on the session. I am having a problem with a null pointer exception. What stumps me is it occurs where I am adding an appointment to the list. Can you see what I am missing?

patientList.add(appt);

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.NullPointerException
business.PatientList.setAppointments(PatientList.java:37)
business.ApptServlet.doGet(ApptServlet.java:72)
business.ApptServlet.doPost(ApptServlet.java:85)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

[ddmeightball]

Ok, I deleted the compiled JSP java files that Tomcat generates for me and deleted my .class files that I compiled and then stopped and started tomcat and now the session works. MAN!!!