怎么这个程序的矩形显示一下就没了
怎么把它一直显示在窗体上，直到关闭窗体。

程序如下：
package TestPrograms;

import java.io.*;
import java.awt.*;
import java.lang.*;
 
public class ColoredTriangle 
{
private Point p1;
private Point p2;
private Point p3;
private Color color;

/*
 * ColoredTriangle():
 */
public ColoredTriangle()
{
Point a=new Point(1,1);
Point b=new Point(2,2);
Point c=new Point(3,3);

setPoint(1,a);
setPoint(2,b);
setPoint(3,c);
setColor(Color.red);

}
/*
 * ColoredTringle()
 */
public ColoredTriangle(Point a,Point b,Point d,Color c)
{
setPoint(1,a);
setPoint(2,b);
setPoint(3,d);
setColor©;
}
/*
 * setPoint():
 */
public void setPoint(int i,Point v)
{
if (i==1)
{
p1=new Point(v.x,v.y);
}

else if(i==2)
{
p2=new Point(v.x,v.y);
}

else if(i==3)
{
p3=new Point(v.x,v.y);
}

else 
{
System.out.print("Unexcept point"+i);
System.exit(i);
}
}
/*
 * getPoint():
 */
public Point getPoint(int i)
{
if(i==1)
{
return p1;
}

else if(i==2)
{
return p2;
}

else if(i==3)
{
return p3;
}
else
{
System.out.print("Unexcept point"+i);
System.exit(i);
return null;
}


}

/*
 * setColor
 */

public void setColor(Color c)
{
color=c;
}

/*
 * getColor():
 */
public Color getColor()
{
return color;
}

/*
 * Paint():
 */

public void paint(Graphics g)
{
Point v1=getPoint(1);
Point v2=getPoint(2);
Point v3=getPoint(3);
Color c=getColor();

g.setColor©;

Polygon t=new Polygon();

t.addPoint(v1.x, v1.y);
t.addPoint(v2.x, v2.y);
t.addPoint(v3.x, v3.y);

g.fillPolygon(t);

}

}

------------------------------------
/**
 * 
 */
package TestPrograms;

import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.lang.*;


/**
 * @author Administrator
 *
 */
public class TestColoredTriangle
{

/**
 * @param args
 */
public static void main(String[] args) throws NullPointerException
{
// TODO 自动生成方法存根

JFrame windows=new JFrame("Triangle");

ColoredTriangle r1=new ColoredTriangle();
ColoredTriangle r2=new ColoredTriangle();

Graphics g=windows.getGraphics();
windows.setSize(400,400);
windows.setVisible(true);
windows.getGraphics();

r1.paint(g);


}
}

程序在Eclipse3.2+jdK1.6.0下通过编译。