It requires us to change some code around in a file to add joptionpane dialog boxes in instead of the fields already there. The following is the exact wording of the assignment:

Look through the source code for the Flora. java file. Insert comment marks (//) at the beginning of all lines involving any of the message boxes, except for the MessageBox declaration statements. Directly underneath the lines that are commented out, insert new code to generate JOptionPane dialog boxes that replace the message boxes. Use the same titles, prompts, and buttons. Do not forget to import the necessary Swing packages.

I am having trouble figuring out how to add a JOptionPane box in. I imported the swing for the joptionpane but I need assistance setting it up for the boxes

String code;
  if (arg == "New Sticker")
     code = "N";
  else
     code = "R";

  if (
        (vin.getText().compareTo("")<1)       ||
        (year.getText().compareTo("")<1)      ||
        (make.getText().compareTo("")<1)      ||
        (model.getText().compareTo("")<1)     ||
        (firstName.getText().compareTo("")<1) ||
        (lastName.getText().compareTo("")<1)  ||
        (address.getText().compareTo("")<1)
     )
  {

     errorBox = new MessageBox(this, "Data Entry Error", "You must complete all fields.");
     errorBox.setVisible(true);
  }
  else
  {
  try
  {
     output.writeUTF(code);
     output.writeUTF(vin.getText());
     output.writeUTF(year.getText());
     output.writeUTF(make.getText());
     output.writeUTF(model.getText());
     output.writeUTF(firstName.getText());
     output.writeUTF(lastName.getText());
     output.writeUTF(address.getText());

         savedBox = new MessageBox(this, "Data Submitted", "The vehicle information has been saved.");
         savedBox.setVisible(true);
      }
      catch(IOException c)
      {
         System.exit(1);
      }
      clearFields();
      }
   }

   public void clearFields()
   {
      //Clear fields and reset the focus
      vin.setText("");
      year.setText("");
      make.setText("");
      model.setText("");
      firstName.setText("");
      lastName.setText("");
      address.setText("");
      vin.requestFocus();
    }
}