Java JComponent不刷新

Question

I've got problem with my class Component. The problem is that my ovals doesn't changing their colors. The function if is observing OVF flag in class Counter. when OVF=true ovals should be red, and when OVF=false ovals should be white. in my GUI i can see only red ovals (even if OVF=false). I try to add repaint() command but red ovals only started blinking. Here is my code:

import java.awt.*;
import javax.swing.*;
import java.util.Observable;


public class Komponent extends JComponent
{
Counter counter3;
public Komponent()
{
    counter3=new Counter();
}
public void paint(Graphics g) 
{
 Graphics2D dioda = (Graphics2D)g;
 int x1 = 85;
 int x2 = 135;
 int y = 3;
 int width = (getSize().width/9)-6;
 int height = (getSize().height-1)-6;

 if (counter3.OVF = true)
 {
 dioda.setColor(Color.RED);
 dioda.fillOval(x1, y, width, height);
 dioda.fillOval(x2, y, width, height);
 }
if (counter3.OVF = false)
{
 dioda.setColor(Color.WHITE);
 dioda.fillOval(x1, y, width, height);
 dioda.fillOval(x2, y, width, height);
}
}
public static void main(String[] arg)
{
 new Komponent();
}
}

what is wrong with that code?

Answer 1

If should be:

if (counter3.OVF == true) { // watch out for = and ==
    // red
}
if (counter3.OVF == false) {
    // white
}

Or simpler:

if (counter3.OVF) {
    // red
} else {
    // white
}

Or simplest:

dioda.setColor(counter3.OVF ? Color.RED : Color.WHITE);
dioda.fillOval(x1, y, width, height);
dioda.fillOval(x2, y, width, height);