请各位帮忙解决一下~我的这代码是用窗体显示图片```可图片出不来~是什么原因呢？

/**
 * @(#)tt.java
 *
 *
 * @author
 * @version 1.00 2008/4/6
 */
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
public class tt extends Frame {
        
    /**
     * Creates a new instance of <code>tt</code>.
     */
    Image img;
    public tt() {
        
        this.setLayout(new FlowLayout());
        this.setSize(720,480);
        this.addWindowListener(new a());
        //this.show();
        this.setVisible(true);
    }
    public void Paint(Graphics g)
    {
        Toolkit tk=Toolkit.getDefaultToolkit();
        Image img=tk.getImage("1.jpg");
        g.drawImage(img,0,20,this);
    }
    public void update(Graphics g)
    {
        this.Paint(g);
    }
   
    public void repaint(Graphics g)
    {
        this.Paint(g);
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        new tt();
    }
}
class a extends WindowAdapter
{
    public void windowClosing(WindowEvent e)
    {
        System.exit(1);
    }
}

import java.awt.*;  
import java.awt.event.*;
import javax.swing.*;

class DrawImage extends Frame  
{  

public static Image img=null;  
public static void main(String[] args)
{  
DrawImage f=new DrawImage();
f.init();
//f.paint();
}  
public void init()  
{  
img=this.getToolkit().getImage("D:/java/1.gif");
setSize(200,200);  
setVisible(true);
this.addWindowListener(new WindowAdapter()  
{  
public void windowClosing(WindowEvent e)  
{  
System.exit(0);  
}  
});     

}  
public void paint(Graphics g)  
{  
  //Container cp=getContentPane();
  getGraphics().drawImage(img,40,40,this);
 
}  
}

Paint()--->paint()

恩..楼上说的没错.我没太注意.paint()函数是系统的不能大写..除非你实现一个Graphics