barheights.java

java源程序 对初学者有很大的帮助 从简单到复杂

//********************************************************************
//  BarHeights.java       Author: Lewis/Loftus
//  
//  Demonstrates the use of conditionals and loops to guide drawing.
//********************************************************************

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

public class BarHeights extends Applet
{
   //-----------------------------------------------------------------
   //  Paints bars of varying heights, tracking the tallest and
   //  shortest bars, which are redrawn in color at the end.
   //-----------------------------------------------------------------
   public void paint (Graphics page)
   {
      final int NUM_BARS = 10, WIDTH = 30, MAX_HEIGHT = 300, GAP =9;
      int tallX = 0, tallest = 0, shortX = 0, shortest = MAX_HEIGHT;
      int x, height;

      Random generator = new Random();
      setBackground (Color.black);

      page.setColor (Color.blue);
      x = GAP;

      for (int count = 0; count < NUM_BARS; count++)
      {
         height = generator.nextInt(MAX_HEIGHT) + 1;
         page.fillRect (x, MAX_HEIGHT-height, WIDTH, height);

         // Keep track of the tallest and shortest bars
         if (height > tallest)
         {
            tallX = x;
            tallest = height;
         }

         if (height < shortest)
         {
            shortX = x;
            shortest = height;
         }

         x = x + WIDTH + GAP;
      }

      // Redraw the tallest bar in red
      page.setColor (Color.red);
      page.fillRect (tallX, MAX_HEIGHT-tallest, WIDTH, tallest);

      // Redraw the shortest bar in yellow 
      page.setColor (Color.yellow);
      page.fillRect (shortX, MAX_HEIGHT-shortest, WIDTH, shortest);
   }
}