Why the paint() method is called two times ?

[supremo]

This code calls two times the paint() method when I run this:

package KLL;
import javax.swing.*;
import java.awt.*;


public class KLL extends JFrame {

static int a;
static int b;
public KLL(){
super();
a=12;
b=20;

setSize(300,300);

setVisible(true);

}

public void paint(Graphics g){

System.out.println(a);
Graphics2D g2;
g2=(Graphics2D) g;
g2.draw3DRect(100, 100, a, b, false);
}

public static void main (String[] args) throws InterruptedException{
KLL K=new KLL();
Thread.currentThread();
Thread.sleep(3000);
a=80;
b=120;
K.repaint();
Thread.sleep(3000);
a=200;
b=120;
K.repaint();
}

}

When using repaint() it is called only 1 time which is understandable. But why when I run this code it is called two times at the beginning ??

[camickr]

I have no idea but that is NOT the way to do custom painting.

Read the section from the Swing tutorial on Custom Painting for the proper way to do this.

[supremo]

Thank you for the answer and the link.

However it is very strange why this behavior is followed in that code....

[Norm]

The JVM AWT engine determines how and when to call paint(); It can merge repaint() requests into a single call to paint().

Bottom-line Not always easy to predict when paint() will be called.

[supremo]

Hm... Thank you.

Interesting...