Java Code:
import java.awt.AlphaComposite;
import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.TexturePaint;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.JTextField;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class ColorComposite extends JFrame {
  MyCanvas canvas;

  JTextField textField;

  float alphaValue = 0.65f;

  public ColorComposite() {
    super();
    Container container = getContentPane();

    canvas = new MyCanvas();
    container.add(canvas);

    JPanel panel = new JPanel();

    JLabel label = new JLabel("Color-Composite: ");

    JSlider slider = new JSlider(JSlider.HORIZONTAL, 0, 100, 65);
    slider.addChangeListener(new ChangeListener() {
      public void stateChanged(ChangeEvent e) {
        JSlider tempSlider = (JSlider) e.getSource();
        alphaValue = (float) (tempSlider.getValue() / 100.0);
        textField.setText(Float.toString(alphaValue));
        canvas.repaint();
      }
    });

    textField = new JTextField("0.65", 4);

    panel.add(label);
    panel.add(slider);
    panel.add(textField);

    container.add(BorderLayout.SOUTH, panel);

    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    setSize(450,450);
    setVisible(true);
  }

  public static void main(String arg[]) {
    new ColorComposite();
  }

  class MyCanvas extends JLabel {
    Rectangle2D rec1, rec2, rec3, rec4, rec5;

    MyCanvas() {
      rec1 = new Rectangle2D.Float(25, 25, 75, 150);
      rec2 = new Rectangle2D.Float(125, 25, 100, 75);
      rec3 = new Rectangle2D.Float(75, 125, 125, 75);
      rec4 = new Rectangle2D.Float(225, 125, 125, 75);
      rec5 = new Rectangle2D.Float(150, 50, 125, 175);

      setBackground(Color.white);
      setSize(400, 225);
    }

    public void paint(Graphics g) {
      Graphics2D g2D = (Graphics2D) g;

      AlphaComposite ac = AlphaComposite.getInstance(
          AlphaComposite.SRC_OVER, alphaValue);
      g2D.setComposite(ac);

      g2D.setStroke(new BasicStroke(5.0f));
      g2D.draw(rec1);

      GradientPaint gp = new GradientPaint(125f, 25f, Color.yellow, 225f,
          100f, Color.blue);
      g2D.setPaint(gp);
      g2D.fill(rec2);

      BufferedImage bi = new BufferedImage(5, 5,
          BufferedImage.TYPE_INT_RGB);
      Graphics2D big = bi.createGraphics();
      big.setColor(Color.magenta);
      big.fillRect(0, 0, 5, 5);
      big.setColor(Color.black);
      big.drawLine(0, 0, 5, 5);
      Rectangle r = new Rectangle(0, 0, 5, 5);

      TexturePaint tp = new TexturePaint(bi, r);

      g2D.setPaint(tp);
      g2D.fill(rec3);

      g2D.setColor(Color.green);
      g2D.fill(rec4);
      g2D.setColor(Color.red);
      g2D.fill(rec5);
    }
  }
}