I am trying to write the simples GUI countdown. I found in Internet some code but it is already too fancy for me. I am trying to keep it as simple as possible. So, I just want to have a window saying "You have 10 second left". The number of second should decrease every second from 10 to 0. I wrote a code. And I think I am close to the working solution. But I still missing something. Could you pleas help me to find out what is wrong? Here is my code:

import javax.swing.*;

public class Countdown {

    static JLabel label;

    // Method which defines the appearance of the window.   
    private static void showGUI() {
        JFrame frame = new JFrame("Simple Countdown");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JLabel label = new JLabel("Some Text");
        frame.add(label);
        frame.pack();
        frame.setVisible(true);
    }

    // Define a new thread in which the countdown is counting down.
    static Thread counter = new Thread() {
        public void run() {
            for (int i=10; i>0; i=i-1) {
                updateGUI(i,label);
                try {Thread.sleep(1000);} catch(InterruptedException e) {};
            }
        }
    };

    // A method which updates GUI (sets a new value of JLabel).
    private static void updateGUI(final int i, final JLabel label) {
        SwingUtilities.invokeLater(new Runnable(i,label) {

            public Runnable(int i, JLabel label) {
                this.i = i;
                this.label = label;
            }

            public void run() {
                label.setText("You have " + i + " seconds.");
            }

        });
    }

    // The main method (entry point).
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                showGUI();
                //counter.start();
            }
        });
        //counter.start();
    }

}

And I have several concrete question about this code:

1. Where should I place the counter.start();? (In my code I put it on 2 places. Which one is correct?)

2. Why compiler complains about the constructor for Runnable? It says that I have an invalid method declaration and I need to specify the returned type.

ADDED: I made the suggested corrections. And then I execute the code and get:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Worker.run(Worker.java:12)

In the Worker.java in the line 12 I have: label.setText("You have " + i + " seconds.");.