Thread sharing in Timer

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.MessageFormat;

import javax.swing.Timer;

public class Sandbox {
  private static int i = 0;
  public static void main(String[] args) {
    ActionListener listener = new ActionListener() {
      @Override public void actionPerformed(ActionEvent event) {
        i++;
        System.out.println(MessageFormat.format(
            "{0}: {1} ms", i, System.currentTimeMillis() % 1000000));
      }
    };
    System.out.println(MessageFormat.format(
        "start: {0} ms", System.currentTimeMillis() % 1000000));
    Timer timer = new Timer(1000, listener);
    timer.start();
    timer = new Timer(1000, listener); /* replace timer */
    timer.start();
    try {
      Thread.sleep(3000);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    System.exit(0);
  }
}

/*
output:

start: 849,378 ms
1: 850,574 ms
2: 850,574 ms     <-- exact same millisecond
3: 851,569 ms
4: 851,570 ms     <-- same millisecond, slight delay
*/