indsættelse af jpg billeder i en GUI

jeg er igang med at lave et tekst-baseret spil, og vil gerne indsætte billeder af de forskellige rum. Alle billederne har samme størrelse (400*400px).

Billedet skal være i den JPanel som hedder picturePanel.

her er min source code:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

/**
* GUI is the class that is responsible of the making a GUI for our game.
*
* @author Jesper Højlund
* @version 0.1
*/
public class GUI
{
    private JFrame frame;
    private JPanel textOutputPanel;
    private JPanel picturePanel; 
    private JPanel textInputPanel;
    private JPanel holderPanel;
    private JPanel statusPanel;
    private JPanel exitsPanel;
    private JPanel healthPanel;
    private JLabel statusLabel;
    private JLabel healthStatusLabel;
    private JLabel healthLabel;
    private JLabel exitsLabel;
    private JLabel exitsStatusLabel;
    private JTextArea textOutput;
    private JTextField textField;
   
   
    /**
    * Create an GUI, show it on screen.
    */
    public GUI()
    {
        makeFrame();
    }


    // ---- implementation of menu functions ----
   
    /**
    * Help function: displays the functions in the game.
    */
    private void showCommands()
    {
        // this is some test output, until we do this properly
        System.out.println("See the commands");
    }
   
    /**
    * Quit function: quit the application.
    */
    private void quit()
    {
        System.exit(0);
    }
   
   
    // test function to see if status panel works
    private void status()
    {
        String test = textField.getText();
        textField.setText("");
        updateStatus(test);
    }
   
   
    private void updateStatus(String test)
    {
        textOutput.setText(test);
    }
   



   
    /**
    * Create the Swing frame and its content.
    */
    private void makeFrame()
    {
        frame = new JFrame("Fire Fighter Bob");
        makeMenuBar(frame);
       

        //prepare the main content pane
        JPanel contentPane = (JPanel)frame.getContentPane();
        contentPane.setLayout(new BorderLayout(2,2));
       
       
        // create the panel with the picture 
        picturePanel = new JPanel();
        contentPane.add(picturePanel, BorderLayout.NORTH);

       
        // create the panel with the text output
        textOutput = new JTextArea(5,1);
        textOutput.setBackground(Color.WHITE);
        textOutput.setBorder
        (
            BorderFactory.createCompoundBorder
            (
                new EtchedBorder(), new EmptyBorder(10, 10, 10, 10)
            )
        );
        contentPane.add(textOutput, BorderLayout.CENTER);


        // create a holder panel for the status (health and exits) and text-input
        holderPanel = new JPanel(new BorderLayout());
        contentPane.add(holderPanel, BorderLayout.SOUTH);
       

        //status panel
        statusPanel = new JPanel(new BorderLayout());
        holderPanel.add(statusPanel, BorderLayout.NORTH);


        //health panel
        healthPanel = new JPanel();
        statusPanel.add(healthPanel, BorderLayout.WEST);
       
        // create the labels with the health
        healthLabel = new JLabel("Health: ");
        healthStatusLabel = new JLabel("100");
       
        healthPanel.add(healthLabel);
        healthPanel.add(healthStatusLabel);
       

        //statusPanel exits
        exitsPanel = new JPanel();
        statusPanel.add(exitsPanel, BorderLayout.EAST);

        // create the labels with the exits
        exitsLabel = new JLabel("Exits: ");
        exitsStatusLabel = new JLabel("north, east, south");
       
        exitsPanel.add(exitsLabel);
        exitsPanel.add(exitsStatusLabel);


        // create the panel with the textinput
        textInputPanel = new JPanel();     
        textField = new JTextField(30);
        textInputPanel.add(textField);
       
        textField.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                status();
            }
        });
        holderPanel.add(textInputPanel, BorderLayout.SOUTH);
       

        // arrange the components and show them
        frame.pack();       
        frame.setVisible(true);
       
       
    }
   
    /**
    * Create the main frame's menu bar.
    */
    private void makeMenuBar(JFrame frame)
    {
        JMenuBar menubar = new JMenuBar();
        frame.setJMenuBar(menubar);
       
        // create the Functions menu
        JMenu functionMenu = new JMenu("Functions");
        menubar.add(functionMenu);
       
        JMenuItem quitItem = new JMenuItem("Quit");
            quitItem.addActionListener(new ActionListener() {
                              public void actionPerformed(ActionEvent e) { quit(); }
                          });
        functionMenu.add(quitItem);
       
        menubar.add(Box.createHorizontalGlue());
       
        JMenu helpMenu = new JMenu("Help");
        menubar.add(helpMenu);
       
        JMenuItem commandsItem = new JMenuItem("Commands");
        commandsItem.addActionListener(new ActionListener()
            {
                public void actionPerformed(ActionEvent e)
                {
                    showCommands();
                }
            }
            );
        helpMenu.add(commandsItem);
    }
}