class Vent5sek implements Runnable {
    @Override
    public void run () {
	try {
	    Thread.sleep(5000);
	} catch (InterruptedException e) {}
	System.exit(0);
    }
}

Thread nedTeller = new Thread(new Vent5sek());
nedTeller.start();

JFrame vindu = new JFrame("Info");
vindu.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel();
vindu.add(panel);

JLabel tekst = new JLabel("xxxx xxxx");
panel.add(tekst);

JButton exit = new JButton("Avslutt");
class Avslutt implements ActionListener {
    @Override
    public void actionPerformed (ActionEvent e) {
	nedTeller.interrupt();
	System.exit(0);
    }
}
exit.addListener(new Avslutt());
panel.add(exit);

vindu.pack();
vindu.setVisible(true);