• The Wrapper Classes e.g. java.lang.Integer class
• The java.util.Vector Class
• The java.lang.String Class
• The java.util.StringTokenizer Class
• The java.io.BufferedReader Class
• The java.lang.Math Class
• The java.util.Random Class

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

         public class Pie extends Applet implements ActionListener
         {
           public int slope;
           public Button go;
           public TextField in;
            
           public void init()
           {
             slope = 0;
             
             go = new Button("Go");
             in = new TextField(5);
             
             add(in); add(go);
             
             go.addActionListener(this);
           }
           
           public void drawPie(Graphics g, int x, int y,
                               int width, int height, int angle)
           {
             // the width of the outer edge
             int bandWidth = width/7;
             int bandHeight = height/7;
             
             // the dimensions of the slices
             int propWidth = width - 2*bandWidth;
             int propHeight = height - 2*bandHeight;
             
           // draw the edge
           g.setColor(Color.red);
           g.fillOval(x , y, width, height);
             
           // the yellow slices
           g.setColor(Color.yellow);
           g.fillArc(x + bandWidth, y + bandHeight,
                     propWidth, propHeight, angle, 90);
             g.fillArc(x + bandWidth, y + bandHeight,
                       propWidth, propHeight, angle + 180, 90);

           // the black slices
           g.setColor(Color.black);
             g.fillArc(x + bandWidth, y + bandHeight,
                       propWidth, propHeight, angle + 90, 90);
           g.fillArc(x + bandWidth, y + bandHeight, 
                     propWidth, propHeight, angle + 270, 90);
           }
           
           public void drawPieSlanted(Graphics g, int x, int y,
                                      int size, int angle, int slope)
           {
             int cos = (int)Math.round((size/2) * Math.cos(slope*Math.PI/180));
             drawPie(g, x, y + (size/2) - cos, size, 2 * cos, angle);
           }
           
           public void paint(Graphics g)
           {
             drawPieSlanted(g, 20, 20, 70, 0, slope);
           }
           
           public void actionPerformed(ActionEvent e)
           {
             int movingMax;
             int movingAngle = Integer.parseInt(in.getText());
 
             movingMax = (int) (movingAngle * Math.random());
             for (slope = 0; slope < movingMax; slope++) {
                 repaint();
                 for (int i = 0; i < 1000000; i++);
             }
           }  
         }