// The "rain" applet

import java.applet.*;
import java.util.*;
import java.awt.*;

public class P6_22 extends Applet {

   private final int MAX_COUNT   = 1000;
   private final int BUSY_WAIT   = 90000000;
   private final int APPLET_SIZE = 500;

   private Random position = new Random();

   private Raindrop[] rain = new Raindrop[5];

   private Graphics page;

   public void init() {

      for (int drop = 0; drop < rain.length; drop++)
         rain[drop] = new Raindrop();
 
      setSize (APPLET_SIZE, APPLET_SIZE);
      setVisible (true);

      page = getGraphics();

   }

   public void start() {

      int count = 1;
      int wait;

      while (count < MAX_COUNT) {
         for (int drop = 0; drop < rain.length; drop++)
            check_drop (rain[drop]);
         count = count + 1;

         draw (page);

         wait = 0;
         while (wait < BUSY_WAIT) {
            wait = wait + 1;
         }
      }
   } 

   public void check_drop (Raindrop drop) {

      if (drop.visible()) {
         drop.ripple();
      } 
      else {
         int x = Math.abs (position.nextInt() % APPLET_SIZE) + 1;
         int y = Math.abs (position.nextInt() % APPLET_SIZE) + 1;
         drop.set_position (x, y);
      }
   } 

   public void draw (Graphics page) {

      page.setColor(getBackground());
      page.fillRect (0, 0, APPLET_SIZE, APPLET_SIZE);
      page.setColor(getForeground());

      for (int drop = 0; drop < rain.length; drop++)
         rain[drop].draw (page);
   } 
} 

class Raindrop {

   private final int MAX_RIPPLE = 30;
   private final int RIPPLE_STEP = 2;

   private static Random new_size = new Random();

   private int current_size = 0;
   private int visible_size = 0;
   private int x = 1, y = 1;

   public boolean visible() {
      return current_size < visible_size;
   } 

   public void set_position (int x_position, int y_position) {

      x = x_position;
      y = y_position;

      visible_size = Math.abs (new_size.nextInt() % MAX_RIPPLE) + 1;

      current_size = 1;
   } 

   public void ripple() {
      x = x - RIPPLE_STEP/2;
      y = y - RIPPLE_STEP/2;
      current_size = current_size + RIPPLE_STEP;
   } 

   public void draw (Graphics page) {
      page.drawOval (x, y, current_size, current_size);
   } 
}