PaintComponent Does not 'Fire'

Hi people

I am attempting my first Java app , a small program to herd sheep.
I am using the MVC framework (also new to me).
In the Graphical View class where I am attempting to set up the frame
for display (I have included the code below) PaintComponent does not
fire.

At teh moment I get frame with a white background and an Exit button.

Can anyone please tell me what I am missing or where I am going wrong.

Many thanks in advance for any assistance offered

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import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.JPanel;

public class ViewGraphical extends JFrame implements Observer
  {
  private Model model; // The Model to register with and
receive updates from
  private Controller controller; // The controller for events
  Image imgDog = null;
  JFrame theFrame;
  JPanel p;
  ImageIcon img;
  ImageIcon imgSheep;

  public ViewGraphical(Model m)
    {
    String lPath = "C:\\.......\\src\\";
    String fileDog = lPath + "Dog.jpg";

    Image imgDog = Toolkit.getDefaultToolkit().getImage(fileDog);
    JFrame theFrame = new JFrame("Text");
    theFrame.setSize(800, 600);
    p = new JPanel();
    p.setBackground(Color.WHITE);
    theFrame.getContentPane().add(p, BorderLayout.CENTER);
    JButton exitButton = new JButton("Exit");
    exitButton.addActionListener(new ExitControl());
    theFrame.getContentPane().add(exitButton, BorderLayout.SOUTH);
    theFrame.setVisible(true);
    theFrame.setAlwaysOnTop(true);
    model = m;
    model.addObserver(this); // Register this class with the Model
    controller = new Controller(model); // Make the Controller using
the same Model
    }

  public void paintComponent(Graphics gr)
    {
    if (imgDog != null)
      {
      gr.drawImage(imgDog,0,0,48,48,this);
      }
    }

  public void update(Observable arg0, Object arg1)
    {
    if(arg1!=null)
      {
      int n;
      try
        {
        }
      catch(NumberFormatException e)
        {
        }
      }
    }
  }