- (J)Components#setVisible() is method for to show or hide (J)Component in the AWT / Swing GUI
- (J)Components#setOpaque() is method for to set transparency for (J)Component,
1. for example JLabel, JViewport, GlassPane are opaque
2. you can pass AlphaComposite (new Color (int, int, int, AlphaComposite)) as transparency parameter for (J)Components
3. notice Transparency by using setOpaque(boolean b) or AlphaComposite is diferrent with compare with Java Translucency
- there are a few code example on this Forum, Oracle tutorial, www.java2s.com (notice examples for Graphics(2D) are in most cases outdated, have to change method paint() to the paintComponent or paintChildren)
If a component is opaque, it's obligated to paint its background completely. Opacity for a given component in Swing indicates whether or not the content behind a given component is visible to the user. E.g. JButton is typically opaque because it completely "hides" whatever happens behind it. On the other hand, if you want to have a rounded button of your own, you need to make sure it is not opaque because there are things behind its bounds that should be visible. I think all Swing components are opaque by default except for JLabel.
The quieter you are, the more you are able to hear.