透明矩形的问题

Question

我一直在搞乱这个问题，需要澄清透明度和显示对象（在这种情况下是矩形）。

    //paintComponent ====================================================================== 
@Override public void paintComponent(Graphics g) {

    super.paintComponent(g);  // Ask parent to paint background.
    Graphics2D g2d = (Graphics2D)g;


    // create the transparency for the text & block
    Composite origComp = g2d.getComposite();
    Composite comp = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.1f);

    // create the rectangle to represent the memory partition block 
    //       x = address position h = amount of memory  (y & w are predefined for the display block)
    Rectangle2D rect = new Rectangle2D.Double(x, y, w, h);  // create the rectangle

    g2d.setComposite(comp);     // set it to transparent
    g2d.setPaint(partColor);    // set it's color
    g2d.fill(rect);             // fill it in
    g2d.setComposite(origComp);

     // draw the text with color, type and size and center the text in the block created above
     g2d.setPaint(Color.black);
     g2d.setFont(new Font("Tahoma", Font.PLAIN, 12));
     g2d.drawString(text, (int)(rect.getCenterX()-text.length()), (int)rect.getCenterY());

}

有人会认为，只要不应用复合材料，就可以使这个矩形看起来几乎透明。出于某种原因，它没有。我错过了什么吗？