Java 繪圖Frame's Paint and Update－溫暖午後的金針田__孕育有趣的創新

Tip: Button 需搭配ActionListener的actionPerformed Event；repaint() 物件是先進入 update() 才進入 paint()，但是Frame預設的update()有自動清理的功能，因此要override update()，如此一來重繪製時才能保留上次的痕跡

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

public class mm extends Frame implements WindowListener, ActionListener{
   int sfg = 0,cnt=0;

   mm(){
       this.setSize(1000,1000);
       this.setLocation(300,200);
       this.setLayout(null);

       /*Button*/
       Button bt = new Button("Paint~");
       bt.setSize(50, 20);
       bt.setLocation(60,60);
       bt.addActionListener(this);/*interface*/

       this.addWindowListener(this);/*interface*/
       this.add(bt);
       this.setVisible(true);
       bt.setVisible(true);
   }

   /*Override Frame*/
   public void update(Graphics g){paint(g);}

   public void paint(Graphics g){
       int x=0,y=0,r=200;
       if(sfg==1){
           Color cr = new Color(fun.Rand(0,255),fun.Rand(0,255),fun.Rand(0,255));
           g.setColor(cr);
           for(int th=0;th<360;th++)
           {
               x = (int)(r*Math.cos(th*3.14159/180))+250+cnt;
               y = (int)(r*Math.sin(th*3.14159/180))+250;
               int r2=5;
               g.drawOval(x-r2, y-r2, r*2, r*2);
           }
       }else if(sfg==2){
           g.setColor(new Color(fun.Rand(0,255),fun.Rand(0,255),fun.Rand(0,255)));
           for(int th=0;th<360;th++)
           {
               x = th+90;
               y = (int)(-50*Math.sin(th*3.14159/180))+250;
               int r2=1;
               g.drawOval(x-r2, y-r2, r2*2+1, r2*2+1);
           }
       }


   }


   public static void main(String[] args)
   {
       mm p = new mm();
   }

   /*Switch*/
   @Override
   public void actionPerformed(ActionEvent e) {
       if(sfg>0)sfg=0;
       sfg++;
       cnt++;
       repaint();
   }

   @Override
   public void windowOpened(WindowEvent e) {
       // TODO Auto-generated method stub

   }

   @Override
   public void windowClosing(WindowEvent e) {
       dispose();
       // TODO Auto-generated method stub

   }

   @Override
   public void windowClosed(WindowEvent e) {
       // TODO Auto-generated method stub

   }

   @Override
   public void windowIconified(WindowEvent e) {
       // TODO Auto-generated method stub

   }

   @Override
   public void windowDeiconified(WindowEvent e) {
       // TODO Auto-generated method stub

   }

   @Override
   public void windowActivated(WindowEvent e) {
       // TODO Auto-generated method stub

   }

   @Override
   public void windowDeactivated(WindowEvent e) {
       // TODO Auto-generated method stub

   }


}