Problem with JFrame, it goes blank

Question

i
My problem is with JFrame, when it's carrying operation which takes a bit of time, if somethhing goes on
top of the frame the frame goes blank, all the components vanished and when the operation is completed the components bacome visible. I dont know why this is happening,. The code is below, since my code is very complicated I am sending some code whcih shows the problem I have, when you press the button it execute's a for loop, whcih takes some time. If you minimize the frame and maximize again, you'll see what I mean.
Please help!!!
Many Thanks
Lilylay
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Frame1 extends JFrame {
JPanel contentPane;
JButton jButton2 = new JButton();
/**Construct the frame*/
public Frame1() {
enableEvents(AWTEvent.WINDOW_EVENT_MASK);
try {
jbInit();
catch(Exception e) {
e.printStackTrace();
/**Component initialization*/
private void jbInit() throws Exception {
//setIconImage(Toolkit.getDefaultToolkit().createImage(Frame1.class.getResource("[Your Icon]")));
contentPane = (JPanel) this.getContentPane();
contentPane.setLayout(null);
this.setSize(new Dimension(407, 289));
this.setTitle("Frame Title");
contentPane.setBackground(SystemColor.text);
contentPane.setForeground(Color.lightGray);
jButton2.setText("Press me!");
jButton2.setBounds(new Rectangle(107, 111, 143, 48));
jButton2.addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(MouseEvent e) {
jButton2_mousePressed(e);
contentPane.add(jButton2, null);
/**Overridden so we can exit when window is closed*/
protected void processWindowEvent(WindowEvent e) {
super.processWindowEvent(e);
if (e.getID() == WindowEvent.WINDOW_CLOSING) {
System.exit(0);
void jButton2_mousePressed(MouseEvent e) {
for(int i=0; i<256898; i++){
for(int j=0; j<5656585; j++){
System.out.println("hello");
public static void main(String [] args){
Frame1 frame=new Frame1();
frame.show();
}

Answer 1

The reason this is happening is because your loop is so intensive that your program doesn't have time to refresh its JFrame. There is no great way to get past this stumbling block without decreasing the efficiency of your code. One possible solution is to call repaint() from within your loop, but of course this slows down your loop.
Hope that helps