[Java] Countdown, Systemzeit ausgeben

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

 
public class Countdown extends Thread implements ActionListener {
 public static void main(String[] args){
 new Countdown().OpenFrame();
 }

 JTextField Count =new JTextField(12);
 JFrame mFrame;
 Thread th1;
 JPanel pNorth,pCenter;
long uhrzeit;

JTextField Tag =new JTextField("Tag",4);
JTextField Monat =new JTextField("Monat",2);
JTextField Jahr =new JTextField("Jahr",2);
JTextField Stunde =new JTextField("Stunde",2);
JTextField Minute =new JTextField("Minute",2);
JButton start = new JButton ("START");

 public void finish(){
 Count.setText ("HAPPY NEW YEAR");
 Count.setForeground (Color.white);
 Count.setBackground (Color.black);
 Count.setForeground (Color.black);
 Count.setBackground (Color.white);
 
 try {
 Thread.sleep(600); //Methode schläft für 600 Millisekunden
 } catch (InterruptedException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();}}
 
 
 
@SuppressWarnings("deprecation")
public void holezeit(){
 int a = Integer.parseInt(Tag.getText());
 int b = ((Integer.parseInt(Monat.getText()))-1);
 int c = ((Integer.parseInt(Jahr.getText()))-1900);
 int d = Integer.parseInt(Stunde.getText());
 int e = Integer.parseInt(Minute.getText());
 java.util.Date sylvester2009= new java.util.Date(c,b,a,d,e); //Hier werden die Einstellung für das Datum getroffen
 long curTime=System.currentTimeMillis()+3600000;
 long diff=sylvester2009.getTime()-curTime;
 long day = diff/86400000;
 long hour = (diff % 86400000)/3600000;
 long min = (diff % 3600000)/60000;
 long sec = (diff % 60000)/1000;
 System.out.printf("Noch %d Tage, %d Stunden und %d Minuten und %d Sekunden",day,hour,min,sec); 
 String hourleft = new String (Long.toString(hour));
 String minutesleft = new String (Long.toString(min));
 String secondsleft = new String (Long.toString(sec));
 Count.setForeground (Color.green);
 Count.setBackground (Color.black);
 Count.setHorizontalAlignment(JTextField.CENTER);
 Count.setText( hourleft + ":" + minutesleft + ":" + secondsleft ); //Uhrzeit wird in Textfeld geschrieben

 try {
 Thread.sleep(1000); //Methode schläft für 1000 Millisekunden
 } catch (InterruptedException h) {
 // TODO Auto-generated catch block
 h.printStackTrace();}
 }

public void OpenFrame(){
 mFrame= new JFrame("Uhrzeit");
 mFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 mFrame.setExtendedState(Frame.MAXIMIZED_BOTH);
 mFrame.setLayout (new BorderLayout());
 mFrame.add(BorderLayout.NORTH, pNorth);
 mFrame.add(BorderLayout.CENTER, pCenter);
 mFrame.setBackground(Color.black);
 mFrame.setForeground(Color.green);
 pNorth.setLayout(new FlowLayout());
 pNorth.add(Tag);
 pNorth.add(Monat);
 pNorth.add(Jahr);
 pNorth.add(Stunde);
 pNorth.add(Minute);
 pNorth.add(start);
 start.addActionListener(this);
 pCenter.setLayout(new GridLayout(1, 1));
 pCenter.add(Count);
 pCenter.setVisible(false);
 }

@Override
public void actionPerformed(ActionEvent b) {
 final String s = b.getActionCommand () ;
 if(s.equals("start")){
 pNorth.setVisible(false);
 pCenter.setVisible(true);
 for(;true; ){
 holezeit(); // Endlosschleife
 } }
}
}