canvastest.java

jbuilder2005

import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class CanvasTest extends Canvas implements KeyListener
{
  int index;
  Color colors[] = {Color.red, Color.green, Color.blue };  //在数组中定义红绿蓝三色
  public void paint(Graphics g)
  {
    g.setColor(colors[index]);                  //设置绘图颜色
    g.fillRect(0,0,getSize().width,getSize().height); //绘制充满画布的实心矩形
  }
  public static void main(String args[])
  {
    Frame f = new Frame("Canvas");
    CanvasTest mc = new CanvasTest();
    f.add(mc,BorderLayout.CENTER);
    f.setSize(150, 150);
    mc.requestFocus();
    mc.addKeyListener(mc);      //注册键盘事件处理者
    f.setVisible(true);
  }
  public void keyTyped(KeyEvent ev)
  {
    index++;                             //循环使用三种颜色
    if (index == colors.length)
    {
      index =0;
    }
    repaint();
  }
  public void keyPressed(KeyEvent ev) {}  //由于未引入适配器，必须把键盘事件都列出
  public void keyReleased(KeyEvent ev) {}
}