Create Gradients in the middle in Java

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
/* w ww  .j  a v  a 2  s  . co  m*/
import javax.swing.JComponent;
import javax.swing.JFrame;

class MyCanvas extends JComponent {
  public void paint(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;

    GradientPaint gp1 = new GradientPaint(0, 0, Color.orange, 0, 20, Color.black, true);


    g2d.setPaint(gp1);
    g2d.fillRect(20, 20, 300, 40);
  }
}

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);
  }
}