how to display different screen

Question

I'm writing a simple program using CardLayout. The main screen should display a button which when pressed would go to the next screen which contains another button for another screen. My problem is that when I run my program the screen is black. I tried following tutorials online to write my own program but I don't seem to find the problem with my code. I don't get any errors when run. Here is my code

//using CardLayout to change screen when action is performed
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JLabel;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.Popup;
import javax.swing.JOptionPane;

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.FlowLayout;

public class CL extends JFrame {

    JPanel cardPanel;
    JPanel cardPanelA;
    JPanel cardPanelB;//to set different screens
    CardLayout cl;
    private JButton button1;
    private JButton button2;
    private JButton change;
    private JLabel label;
    private JTextField textField1;
    private JTextField textField2;
    JButton button;

    public CL() {
        super("This is a sample");

        cardPanel = new JPanel();
        cardPanelA = new JPanel();
        cardPanelB = new JPanel();

        cl = new CardLayout();
        cardPanel.setLayout(cl);

        button1 = new JButton("button1");
        button2 = new JButton("button2");
        change = new JButton("change screen");
        label = new JLabel("this is a label");
        textField1 = new JTextField(10);
        textField2 = new JTextField("enter text", 6);

        cardPanelA.add(change);
        cardPanelA.add(label);
        cardPanelA.add(textField1);
        cardPanelA.add(textField2);
        cardPanelB.add(button1);
        cardPanelB.add(button2);

        cardPanel.add(cardPanelA);
        cardPanel.add(cardPanelB);

        JPanel panel1 = new JPanel();
        button = new JButton("initial button");
        panel1.add(button);

        theHandler handler = new theHandler();//make action listener
        change.addActionListener(handler);
        button1.addActionListener(handler);
        button2.addActionListener(handler);
        button.addActionListener(handler);
        /*
        getContentPane().add(panel1, BorderLayout.NORTH);
        getContentPane().add(cardPanelA, BorderLayout.NORTH);
        getContentPane().add(cardPanelB, BorderLayout.NORTH);
        */
    }

    private class theHandler implements ActionListener {
        public void actionPerformed(ActionEvent event) {

            if (event.getSource() == button) {
                cl.show(cardPanel, "Panel A");
            }
            if (event.getSource() == change) {
                cl.show(cardPanelB, "panelB");
            }
            if (event.getSource() == button2) {
                cl.show(cardPanel, "PanelA");
            }
            if (event.getSource() == button1) {
                JOptionPane.showMessageDialog(null, "this is the second screen");
            }

        }
    }

}

/*way to use CardLayout: create a CardLayout manager and create a bunch of different JPanels which * would each be a different screen. Make a panel that stores the CardLayout as the layout. * Add the different elements to each Panel(buttons, textfields) and then add the panels to the JPanel that stores * the CardLayout */

import javax.swing.JFrame;

public class CardTest {
    public static void main(String[] args) {

        CL object = new CL();
        object.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        object.setSize(400, 400);
        object.setVisible(true);

    }
}

It might be something simple but I'm not sure of what it is. Some advice would be appreciated.

Answer 1

Make sure you add your panels to the frame

    add(cardPanel);

Without that no components will be shown