How to stop a software with a timer repeat over and over?

Question

I have created a software timer and when it goes zero it's going to start a new login screen. The problem is the login comes over and over again. How to stop this?

class DisplayCountdown extends TimerTask {
 int seconds = 0005;
 public void run() {
 if (seconds > 0) {
 int hr = (int) (seconds / 3600);
 int rem = (int) (seconds % 3600);
 int mn = rem / 60;
 int sec = rem % 60;
 String hrStr = (hr < 10 ? "0" : "") + hr;
 String mnStr = (mn < 10 ? "0" : "") + mn;
 String secStr = (sec < 10 ? "0" : "") + sec;
 seconds--;
 lab.setText(hrStr + " : " + mnStr + " : " + secStr + "");
 } else {
 login ty = new login();
 login.scname.setText(scname.getText());
 login.scnum.setText(scnum.getText());
 login.mar.setText(jTextField1.getText());
 ty.setVisible(true);
 dispose();
 }
 }
}

Answer 1

This is violating the single thread rules of Swing - Updating the UI out side the context of the Event Dispatching Thread.

Instead of TimerTask, you should be using a javax.swing.Timer.

javax.swing.Timer swingTimer = new javax.swing.Timer(500, new ActionListener() {
 public void actionPerformed(ActionEvent evt) {
 if (seconds > 0) {
 //...
 } else {
 ((javax.swing.Timer)evt.getSource()).stop();
 //...
 }
 }
});

Take a look at Concurrency in Swing

Answer 2

It is not clear what the code is but can't you use the "cancel()" method of the TimerTask class to cancel it?

Answer 3

You need to keep reference of previous Login Screen and dispose it before making a new one;