Create a transparent color and paint BufferedImage in Java

//  w  ww.ja va 2s. c  o  m
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;

import javax.swing.JComponent;
import javax.swing.JFrame;

class MyCanvas extends JComponent {
  public void paint(Graphics g) {
    BufferedImage bimage = new BufferedImage(200, 200,
        BufferedImage.TYPE_BYTE_INDEXED);
    Graphics2D g2d = bimage.createGraphics();

    Color transparent = new Color(0, 0, 0, 0);
    g2d.setColor(transparent);
    g2d.setComposite(AlphaComposite.Src);
    g2d.fill(new Rectangle2D.Float(20, 20, 100, 20));
    g2d.dispose();

  }
}

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);
  }
}