JPanel does not appear when i try to add it to ContentPane

Question

I'm having a problem trying to change JPanels by using buttons. I have a JFrame with 2 panels, 1 of them is for the buttons, which i want them to always be showed. The other one is the one that i will be switching everytime i press one ot the buttons of the other panel. The problem is that everytime i press them nothing really ever displays, i keep my buttons but the other panel that i call does not appear.

Code for one of the buttons is as follows

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        ReparacaoPanel r = new ReparacaoPanel(this, this.jPanel1);
        this.getContentPane().remove(this.jPanel1);
        this.getContentPane().add(r);
        //this.setContentPane(r);
        this.visiblePanel.setVisible(false);
        this.visiblePanel = r;
        this.pack();
        this.setVisible(true);

        r.setLocation(200, 200);
        this.getContentPane().revalidate();
        this.repaint();
    }

If i try to use "this.setContentPane(r);" (it sets the frame to only show the panel) the panel shows. But when i try to call it as i'm trying to do in the code above nothing is showed apart from the panel that has the buttons.

I have no idea what i'm doing wrong, it does not seem to be a problem with the JPanel that i'm trying to call as it shows if used alone.

Anyone can help me out?

Answer 1

Consider this working example for switching manually between panels. Which produces this output.

.........

Some tiny NumberPanel

Every new instance shows another number in the center.

import javax.swing.JPanel;
public class NumberPanel extends JPanel {
    private static int counter = 0;
    public NumberPanel() {
        setLayout(new BorderLayout(0, 0));
        JLabel lblNewLabel = new JLabel("" + counter++);
        lblNewLabel.setHorizontalAlignment(SwingConstants.CENTER);
        add(lblNewLabel);
    }
}

Setting up a frame

private void initialize() {
    frame = new JFrame();
    frame.setBounds(100, 100, 450, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = new JPanel();
    frame.getContentPane().add(panel, BorderLayout.SOUTH);

    JButton btnNewButton = new JButton("New button");
    btnNewButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            frame.getContentPane().remove(numberPanel);
            numberPanel = new NumberPanel();
            frame.getContentPane().add(numberPanel, BorderLayout.CENTER);
            frame.pack();
        }
    });
    panel.add(btnNewButton);

    numberPanel = new NumberPanel();
    frame.getContentPane().add(numberPanel, BorderLayout.CENTER);
    frame.pack();
}

Testprogram

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TestPanelSwitch {
    private JFrame frame;
    private NumberPanel numberPanel;
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    TestPanelSwitch window = new TestPanelSwitch();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
    public TestPanelSwitch() {
        initialize();
    }
    private void initialize() {
        // see above
    }
}

Back to the Question

I think you only need to pack your frame, like in the anonymous ActionListener.

frame.getContentPane().remove(numberPanel);
numberPanel = new NumberPanel();
frame.getContentPane().add(numberPanel, BorderLayout.CENTER);
frame.pack();

EDIT

As leonidas mentioned it is also possible to revalidate the frame. This requires only to replace the upper call to pack by theese.

frame.invalidate();
frame.validate();