Draw ten rectangles with different levels of transparency in Java

// w  w  w . jav  a2  s . c  o m
import java.awt.AlphaComposite;
import java.awt.Graphics;
import java.awt.Graphics2D;

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

class MyCanvas extends JComponent {
  public void paint(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;
    for (int i = 1; i <= 10; i++) {
      g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, i * 0.1f));
      g2d.fillRect(50 * i, 20, 50, 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);
  }
}