How to make JFrame transparent?

If you do not have any objection in using restricted API classes then you can do this with AWTUtilities class and setWindowOpacity() method of that class. Here and here is a tutorial on how to use it? And here is the version using Java native access.

code example

public static void main(String args[]) {
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            javax.swing.JFrame fr = new NewJFrame();
            com.sun.awt.AWTUtilities.setWindowOpacity(fr, 0.7 f);
            fr.setVisible(true);
        }
    });
}

I found another solution.

Set the background color of your frame to

// Set the frame background color to a transparent color
yourFrameHere.setBackground(new Color(0, 0, 0, 0));

And remember to set the opacity off of the contentpane (your JPanel or other component)

// turn off opacity of the content pane
yourContentPaneHere.setOpaque(false);