java - how to put a timer on a JLabel to update itself every second

Question

I created a game and in my swing GUI interface I want to put a timer. The way I do this at the moment is have a field with the current time , gotten with System.currentTimeMillis() which gets it's value when the game starts .In the method of my game i put the System.currentTimeMillis()- field; and it tells you the current time passed since the game started.

Nevertheless, how do get this to update itself every second lets say, so the JLabel will have : timePassed: 0s , timePassed: 1s and so on. Have in mind that i don't use threads in my game at any point.

EDIT: thank you all for your kind suggestions. I used a combination of your answers please give me some feedback.

I have the JLabel as a field called time. (else i cant handle it).

time = new JLabel("Time Passed:  " + timePassed() + " sec");
panel_4.add(time);

ActionListener actionListener = new ActionListener() {
    public void actionPerformed(ActionEvent actionEvent) {
        time.setText("Time Passed: " + timePassed() + " sec");
    }
};

Timer timer = new Timer(1000, actionListener);
timer.start();

Answer 1

Have a look at the swing timer class. It allows to setup recurring tasks quite easily.