Translate with AffineTransform in Java

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
/*from  w w w.  j  a  v a 2s  .  c o m*/
import javax.swing.JComponent;
import javax.swing.JFrame;

class MyCanvas extends JComponent {
  public void paint(Graphics g) {
    AffineTransform atrans = null;

    Graphics2D g2d = (Graphics2D) g;
    atrans = AffineTransform.getTranslateInstance(50, 100);
    g2d.fillRect(50, 50, 100, 50);
    if (atrans != null)
      g2d.setTransform(atrans);

    g2d.fillRect(50, 50, 100, 50);
  }
}

public class Main {
  public static void main(String[] a) {
    JFrame window = new JFrame();
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    window.setBounds(30, 30, 450, 450);
    window.getContentPane().add(new MyCanvas());
    window.setVisible(true);
  }
}