GUI runtime error

[Mark Phylus]

My program compiles fine but gives me a runtime error.
1. Can anyone explain to me what the error means?
2. Kindly help me fix it.
I do appreciate this. here is the code
Thanks.

 
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class NameGui
{
   public static void main(String[] args)
   {
       FullNameGui f = new FullNameGui();
       f.setVisible(true);
   }
}  // end of NameGui

/*************************************************************/
class FullNameGui extends JFrame
                  implements ActionListener
{
//***************************************************************
//data members:
   private JTextField title, first, last, middle, formalName;
   private JButton formalnameButton;
   FullName name;
//****************************************************************
/****** Constructor *********/
   public FullNameGui()// constructor
   {
// set up the frame properties
      setSize(300,250);    
      setLocation(20,20);
      setTitle("Full Name GUI");
      setResizable(false);
      setDefaultCloseOperation(EXIT_ON_CLOSE);
// establish container & properties
      Container cp = getContentPane();
      cp.setLayout(new FlowLayout());
      cp.setBackground(Color.WHITE);
// add first name information to GUI:  "first" field
      cp.add(new JLabel("First Name"));
      first = new JTextField(15);
      cp.add(first);  
// add middle name information to GUI:  "middle" field
      cp.add(new JLabel("Middle Name"));
      middle = new JTextField(14);
      cp.add(middle);
// add last name information to GUI:"last" field
      cp.add(new JLabel("Last Name"));
      last = new JTextField(16);
      cp.add(last);
// place text field for "formal name" in GUI:  "formal name" field
      cp.add(new JLabel("Formal Name"));
      formalName = new JTextField(25);
      cp.add(formalName);
// add button to "call" for processing to be done
      formalnameButton = new JButton("get Formal Name");
      cp.add(formalnameButton);
      formalnameButton.addActionListener(this);
   } // end of constructor 

/********   actionPerformed method **************/
public void actionPerformed(ActionEvent e)
{
String fname = first.getText().trim();  // retrieve text from "first" field
String lname = last.getText().trim();   // retrieve text from "last" field
String t = title.getText().trim();      // retrieve text from "title" field
String mname = middle.getText().trim(); // retrieve text from "middle"field
 
    if (mname == "")  // middle name field empty   
     name = new FullName(fname,lname); // call to two argument constructor 
    else                       // middle name field has entry
   name = new FullName(fname,mname,lname);//call to three argument
                                          //constructor
      name.setTitle(t);          // use t to set the title for the name
/* set the text in the "formal name" field */
      formalName.setText(name.FormalName());  
  
   }  // end of actionPerformed
}  // end of FullNameGui

[ May 03, 2004: Message edited by: Mark Phylus ]

[Michael Dunn]

You would be getting a NullPointerException here
String t = title.getText().trim();
'title' has not been created, or added to the GUI

[Mark Phylus]

Thanks