Question

I need a timer implemented in my application, which will do a countdown from 10 sec – 0 sec.
and, display the countdown in a JLabel.

Here’s my implementation;

...
Timer t = new Timer(1000, new List());
        t.start();

}

class List implements ActionListener{

    @Override
    public void actionPerformed(ActionEvent e) {
        int sec = 0;
        label.setText(""+sec);
        // Do a if- condition check to see if the clock has reached to, and then stop

    }

}

I was expecting the JLabel to start counting from 0 – 10 and then stop. But it doesn’t. The JLabel set the value 0 and it doesn’t get incremented.

UPDATE 1

    t = new Timer(1000, new Listner());
    t.start();


}

class Listner implements ActionListener{
    private int counter = 0;
    @Override
    public void actionPerformed(ActionEvent e) {
        lable.setText(""+ (counter++));

        if (counter == 10)
              t.removeActionListener(this);

    }

}

Answer 1

You are not storing nor incrementing secs anywhere so I don’t see how it should get updated, try with

Timer timer;

void start() {
  timer = new Timer(1000,new List());
}

class List implements ActionListener {
    private counter = 0;
    @Override
    public void actionPerformed(ActionEvent e) {
        label.setText(""+counter++);

        if (counter == 10)
          timer.removeActionListener(this);
    }
}

Mind that you need to store a reference to the timer somewhere to be able to remove the listener from it once countdown finished.