orgillion orgillion - 22 days ago 18
Java Question

JPanel inside a JPanel inside a JTabbedPane doesn't show up

I have a JPanel (firstPanel) which is embedded into an other JPanel (secondPanel). I want to create a JTabbedPane with two tabs: one for the firstPanel and one for the secondPanel.
However, when I switch to secondPanel, the embedded firstPanel won't show up.

import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;


public class Application extends JFrame
{
public Application()
{
setDefaultCloseOperation(EXIT_ON_CLOSE);
setMinimumSize(new Dimension(300, 300));


JPanel firstPanel = new JPanel();
firstPanel.add(new JLabel("first"));

JPanel secondPanel = new JPanel();

// JPanel thirdPanel = new JPanel();
// thirdPanel.add(new JLabel("third"));
//
// secondPanel.add(thirdPanel);
secondPanel.add(firstPanel);
secondPanel.add(new JLabel("second"));

JTabbedPane mainPanel = new JTabbedPane();
mainPanel.addTab("First", firstPanel);
mainPanel.addTab("Second", secondPanel);

this.add(mainPanel);
}


public static void main(String[] args)
{
Application app = new Application();
app.pack();
app.setVisible(true);
}

}


When I add the thirdPanel instead of the first, it works as expected.
Am I missing something obvious?
Thanks you!

Answer

This is because you are trying to add a single panel to two different parents, one being your secondPanel, and the other being your tab. You can't do that.

Can I ask why you think you want to do this? There is probably a better solution out there for you.

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