Animated Clock JAVA

import java.awt.BasicStroke; 
import java.awt.Color; 
import java.awt.Font;
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.RenderingHints; 
import java.util.Calendar;
import javax.swing.JFrame; 
import javax.swing.JPanel;
class Clock extends JPanel implements Runnable
{
private Thread thread;
private Calendar calendar;
private int fontsize = 15; 
private int fontPadding = 20;
public Clock() 
{ 
setBackground(Color.BLACK); 
thread = new Thread(this); 
thread.start();
}
public void run() 
{ 
while (true) 
{
calendar = Calendar.getInstance(); 
repaint();
try
{
Thread.sleep(1000);
}
catch (InterruptedException e)
{
e.printStackTrace();
} 
}
}
protected void paintComponent(Graphics g) 
{ 
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g; 
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON); 
int width = getWidth();
int height = getHeight();
int radius = Math.min(width, height) / 2 - fontPadding; 
int x = width / 2 - radius;
int y = height / 2 - radius; 
g2.setColor(Color.BLUE); 
g2.drawOval(x, y, radius * 2, radius * 2);
Font font = new Font("Ariel", Font.BOLD, fontsize); 
g2.setFont(font);
g2.setColor(Color.PINK); 
for (int i = 1; i <= 12; i++) 
{
double angle = (i - 3) * 30 * Math.PI / 180;
int x1 = (int) (width / 2 + Math.cos(angle) * (radius - fontPadding)); 
int y1 = (int) (height / 2 + Math.sin(angle) * (radius - fontPadding)); 
String number = Integer.toString(i);
int stringWidth = g2.getFontMetrics().stringWidth(number); 
int stringHeight = g2.getFontMetrics().getAscent();
g2.drawString(number, x1 - stringWidth / 2, y1 + stringHeight / 2);
}
int hour = calendar.get(Calendar.HOUR);
int minute = calendar.get(Calendar.MINUTE); 
int second = calendar.get(Calendar.SECOND);
double hourAngle = (hour + minute / 60.0) * 30.0; 
double minuteAngle = (minute + second / 60.0) * 6.0; 
double secondAngle = second * 6.0;
drawHand(g2, x + radius, y + radius, hourAngle, radius * 0.5, 6);
drawHand(g2, x + radius, y + radius, minuteAngle, radius * 0.7, 4);
drawHand(g2, x + radius, y + radius, secondAngle, radius * 0.9, 2);
}
private void drawHand(Graphics2D g2, int x, int y, double angle, double length, 
int width) 
{ 
angle = Math.toRadians(angle - 90);
int x2 = (int) (x + length * Math.cos(angle)); 
int y2 = (int) (y + length * Math.sin(angle)); 
g2.setStroke(new BasicStroke(width));
g2.drawLine(x, y, x2, y2);
}
public static void main(String[] args) 
{
JFrame frame = new JFrame("Clock Animation "); 
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
frame.setSize(400, 400);
frame.setResizable(false); 
frame.setLocationRelativeTo(null); 
frame.add(new Clock()); 
frame.setVisible(true);
}
}