Java Swing How to - Refresh with swing Timer

Question

We would like to know how to refresh with swing Timer.
Answer

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/* w  ww.  j  a  va 2  s .  com*/
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;

public class Main extends JFrame {
  JFrame frame = new JFrame();
  public Main() {
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(new Panel());
    frame.pack();
    frame.setVisible(true);
  }
  public static void main(String[] args) {
    new Main();
  }
}
class Panel extends JPanel {
  Timer timer;
  Panel() {
    setBackground(Color.BLACK);
    setForeground(Color.WHITE);
    refreshScreen();
  }
  @Override
  protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.setFont(new Font("arial", Font.PLAIN, 24));
    g.drawString("java2s.com", 200, 200);
  }
  public void refreshScreen() {
    timer = new Timer(0, new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        repaint();
      }
    });
    timer.setRepeats(true);
    // Aprox. 60 FPS
    timer.setDelay(17);
    timer.start();
  }
  @Override
  public Dimension getPreferredSize() {
    return new Dimension(650, 480);
  }
}