A Simple Container
Swing provides for grouping other components together. In AWT, such components extended java.awt.Container and included Panel, Window, Frame, and Dialog. With Swing, you get a whole new set of options, providing greater flexibility and power.
import javax.swing.*;
import java.awt.*;
public class OpaqueExample extends JFrame {
public OpaqueExample() {
super("Opaque JPanel Demo");
setSize(400, 200);
setDefaultCloseOperation(EXIT_ON_CLOSE);
// Create two JPanels (opaque), one containing another opaque JPanel and
// the
// other containing a nonopaque JPanel.
JPanel opaque = createNested(true);
JPanel notOpaque = createNested(false);
// Throw it all together.
getContentPane().setLayout(new FlowLayout());
getContentPane().add(opaque);
getContentPane().add(notOpaque);
}
public static void main(String[] args) {
OpaqueExample oe = new OpaqueExample();
oe.setVisible(true);
}
// Create a JPanel containing another JPanel. The inner JPanel's opacity is
// set
// according to the parameter. A JButton is placed inside the inner JPanel
// to give
// it some content.
public JPanel createNested(boolean opaque) {
JPanel outer = new JPanel(new FlowLayout());
JPanel inner = new JPanel(new FlowLayout());
outer.setBackground(Color.white);
inner.setBackground(Color.black);
inner.setOpaque(opaque);
inner.setBorder(BorderFactory.createLineBorder(Color.gray));
inner.add(new JButton("Button"));
outer.add(inner);
return outer;
}
}
