flicker in my program

[Adewale Adebusoye]

Hi..i have a program to draw recursive shapes. It draws ok but the drawing flickers and then disappears. I'll put my code below..please id really appreciate your help..thanks.

  import javax.swing.*;
import java.awt.*;
 
/*******************************************************************************
 * if this code dosent work then i am going to stop the IT buisness and become a
 * rap artist. Thats right im gonna sing gangsta rap instead
 ******************************************************************************/
public class Triangle {
Point p1, p2, p3;
 
JFrame frame;
 
Triangle() {
// create new points
p1 = new Point(50, 50);
p2 = new Point(350, 50);
p3 = new Point(200, 350);
frame = new JFrame("Recursive Triangles");
frame.setBounds(100, 100, 400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
// draw on the frame
draw(p1, p2, p3, 3, frame);
}
 
void draw(Point p1, Point p2, Point p3, int n, JFrame f) {
if (p1 == null || p2 == null || p3 == null || f == null) {
System.exit(1);
}
 
if (n > 0) {
int x1 = p1.x;
int y1 = p1.y;
int x2 = p2.x;
int y2 = p2.y;
int x3 = p3.x;
int y3 = p3.y;
Graphics g = frame.getGraphics();
g.drawLine(x1, y1, x2, y2);
g.drawLine(x2, y2, x3, y3);
g.drawLine(x3, y3, x1, y1);
 
Point q = midPoint(p1, p2);
draw(p1, p3, q, n - 1, frame);
draw(p2, p3, q, n - 1, frame);

}
 
}
 
public Point midPoint(Point p1, Point p2) {
 
int x1 = p1.x;
int y1 = p1.y;
int x2 = p2.x;
int y2 = p2.y;
return new Point((x1 + x2) / 2, (y1 + y2) / 2);
}

public static void main(String args[]){
new Triangle();
}
 
}
  

[Tim LeMaster]

You draw your triangle once and nothing ever redraws it.

Here is a quick and dirty version but it works -

Warning this code just WORKS its not good, it doesn't deal with resizing the window, and setting n above 10 causes serious performance problems on my machine.

Now where is my rap song

import javax.swing.*;
import java.awt.*;
 
/**
 * ***************************************************************************** *
 * if this code dosent work then i am going to stop the IT buisness and become a *
 * rap artist. Thats right im gonna sing gangsta rap instead
 * *****************************************************************************
 */
public class Triangle 
{
Point p1, p2, p3;
JFrame frame;
 
Triangle()
{
// create new points
p1 = new Point(50, 50);
p2 = new Point(350, 50);
p3 = new Point(200, 350);
frame = new JFrame("Recursive Triangles");
frame.setBounds(100, 100, 400, 400);

frame.getContentPane().add(new TrianglePanel(p1, p2, p3, 10));

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
 
public static void main(String args[])
{
new Triangle();
}
}

import java.awt.Graphics;
import java.awt.Point;
 
import javax.swing.JPanel;
 
public class TrianglePanel extends JPanel
{
private static final long serialVersionUID = 4289532818077961162L;
 
private Point p1, p2, p3;
private int n;

public TrianglePanel(Point p1, Point p2, Point p3, int n)
{
this.p1 = p1;
this.p2 = p2;
this.p3 = p3;
this.n = n;
}

protected void paintComponent(Graphics g)
{
draw(p1, p2, p3, n, g);
}

void draw(Point p1, Point p2, Point p3, int n, Graphics g)
{
if (n > 0)
{
int x1 = p1.x;
int y1 = p1.y;
int x2 = p2.x;
int y2 = p2.y;
int x3 = p3.x;
int y3 = p3.y;
 
g.drawLine(x1, y1, x2, y2);
g.drawLine(x2, y2, x3, y3);
g.drawLine(x3, y3, x1, y1);
Point q = midPoint(p1, p2);
draw(p1, p3, q, n - 1, g);
draw(p2, p3, q, n - 1, g);
}
}
 
public Point midPoint(Point p1, Point p2)
{
int x1 = p1.x;
int y1 = p1.y;
int x2 = p2.x;
int y2 = p2.y;
return new Point((x1 + x2) / 2, (y1 + y2) / 2);
}
}

[ October 18, 2006: Message edited by: Tim LeMaster ]
[ October 18, 2006: Message edited by: Tim LeMaster ]

[Adewale Adebusoye]

Thanks tim...but the draw method has to follow this format:

draw(Point p1, Point p2, Point P3, int n, JFrame w)

Since its for an assignment.

Thanks