import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class VisualizingLinkedListsApplet extends Applet 
                                          implements ActionListener,
                                                     ItemListener {


  String[] imageName = { "original", "empty","addLast","addFirst",
                    "add", "removeFirst", "removeLast", "remove" }; 

  List imageList;
  TextField inputImg;
  Label inputLabel;
  Button imageButton[];

  DrawPanel drawPanel;
  Panel buttonPanel;
  Panel promptPanel;
  
  public void init() {  
      buttonPanel = new Panel();
      promptPanel = new Panel();


      drawPanel = new DrawPanel();
      drawPanel.imageDisp = getImage(getCodeBase(), imageName[0] + ".gif");

      setLayout(new BorderLayout());


      buttonPanel.setLayout(new GridLayout(1,8));

      promptPanel.setLayout(new FlowLayout(FlowLayout.LEFT,10,10));

      imageButton = new Button[imageName.length];

      imageList = new List(imageName.length);

      inputLabel = new Label("Type operation and press return");
      inputImg = new TextField(20);


      add("Center",drawPanel);

      for (int i = 0; i < imageName.length; i++) {
        imageButton[i] = new Button(imageName[i]);
        buttonPanel.add(imageButton[i]);
        imageButton[i].addActionListener(this);
      }


      add("North",buttonPanel);

      for (int i = 0; i < imageName.length; i++) 
        imageList.add(imageName[i]);

      add("East",imageList);
      imageList.addItemListener(this);

      promptPanel.add(inputLabel);

      promptPanel.add(inputImg);
 
      add("South",promptPanel);

      // anonymous inner class
      inputImg.addActionListener(  new ActionListener() {
            public void actionPerformed( ActionEvent e )    {
              drawPanel.imageDisp = getImage(getCodeBase(), inputImg.getText() + ".gif"); 
              inputImg.setText("");
              drawPanel.repaint();
            }
         }
      );
  } 

  public void actionPerformed(ActionEvent e) {

    for (int i = 0; i < imageButton.length; i++)
      if (e.getSource().equals(imageButton[i])) {
         drawPanel.imageDisp = getImage(getCodeBase(), imageName[i] + ".gif");   
         drawPanel.repaint();      
     }
  }

  public void itemStateChanged(ItemEvent ie) {

    drawPanel.imageDisp= getImage(getCodeBase(), imageList.getSelectedItem() + ".gif"); 
    drawPanel.repaint();
  }
}

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class DrawPanel extends Panel implements MouseListener {

  public Image imageDisp;

  private Point lineStart = new Point(0, 0); // Line start point
  private Graphics g; // Create a Graphics object for drawing


  public DrawPanel() {

      setBackground(Color.white);

      addMouseMotionListener(
         new MouseMotionAdapter() {
            public void mouseDragged( MouseEvent e ) {

               g = getGraphics(); // Get graphics context

               g.setColor(Color.red);

               g.drawLine(lineStart.x, lineStart.y,
                          e.getX(), e.getY());
    
               lineStart.move(e.getX(), e.getY());

               // Dispose this graphics context
               g.dispose();
            }   
         }  
      );

      addMouseListener(this);
  }

  public void paint(Graphics g) {

    g.drawImage(imageDisp, 10, 10,this);       
  } 

  public void mousePressed(MouseEvent e) {

     lineStart.move(e.getX(), e.getY());
  }

  public void mouseReleased(MouseEvent e) {
  }

  public void mouseEntered(MouseEvent e) {
  }

  public void mouseExited(MouseEvent e) {
  }

  public void mouseClicked(MouseEvent e) {
  }
}