How to Change java Cardlayout from another separate class

Question

Please I have been trying to switch CardLayout from another class (JPanel) which is one of the card on the CardLayout, I have search and made research about this for a very

Answer 1

In your provided code, you never added FirstCard and SecondCard, to the JPanel having layout set to CardLayout. Since what you writing is this :

jPanel1.add(jPanel2, "card2");

here jPanel2 is an instance of JPanel, as you have initialized this in your TestmyClass Class, as :

jPanel2 = new javax.swing.JPanel();

instead I guess what you should be writing is :

jPanel2 = new SecondCard(passPanelWithCardLayoutAsArgument); // So that you can manoeuvre around b/w other JPanels

Here is a small working example for your help :

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class CardLayoutExample
{
    private JPanel contentPane;
    private MyPanel panel1;
    private MyPanel panel2;
    private MyPanel panel3;

    private void displayGUI()
    {
        JFrame frame = new JFrame("Card Layout Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel contentPane = new JPanel();
        contentPane.setBorder(
            BorderFactory.createEmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new CardLayout());

        panel1 = new MyPanel(contentPane
                , Color.RED.darker().darker());
        panel2 = new MyPanel(contentPane
                , Color.GREEN.darker().darker());
        panel3 = new MyPanel(contentPane
                , Color.DARK_GRAY); 

        contentPane.add(panel1, "Panel 1"); 
        contentPane.add(panel2, "Panel 2");
        contentPane.add(panel3, "Panel 3");         

        frame.setContentPane(contentPane);      
        frame.pack();   
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new CardLayoutExample().displayGUI();
            }
        });
    }
}

class MyPanel extends JPanel 
{

    private JButton jcomp1;
    private JPanel contentPane;
    private Color backgroundColour;

    public MyPanel(JPanel panel, Color c) 
    {   
        contentPane = panel;
        backgroundColour = c;

        setOpaque(true);
        setBackground(backgroundColour);

        //construct components
        jcomp1 = new JButton ("Show New Panel");
        jcomp1.addActionListener( new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                CardLayout cardLayout = (CardLayout) contentPane.getLayout();
                cardLayout.next(contentPane);
            }
        });

        add(jcomp1);
    }

    @Override
    public Dimension getPreferredSize()
    {
        return (new Dimension(500, 500));
    }
}

LATEST EDIT : *Using your components and trying to put that into CardLayout, with this code : *

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class CardLayoutExample
{
    private JPanel contentPane;
    private FirstCard panel1;
    private SecondCard panel2;

    private void displayGUI()
    {
        JFrame frame = new JFrame("Card Layout Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel contentPane = new JPanel();
        contentPane.setBorder(
            BorderFactory.createEmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(new CardLayout());

        panel1 = new FirstCard(contentPane);
        panel2 = new SecondCard(contentPane);

        contentPane.add(panel1, "Panel 1"); 
        contentPane.add(panel2, "Panel 2");     

        frame.setContentPane(contentPane);      
        frame.pack();   
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new CardLayoutExample().displayGUI();
            }
        });
    }
}

class FirstCard extends javax.swing.JPanel 
{
    private javax.swing.JTextField addField;
    private javax.swing.JTextField nameField;
    private javax.swing.JTextField occField;
    private javax.swing.JTextField phoneField;
    private javax.swing.JLabel nameLabel;
    private javax.swing.JLabel addLabel;
    private javax.swing.JLabel occLabel;
    private javax.swing.JLabel phoneLabel;
    private JPanel centerPanel;
    private JPanel contentPane;
    private JButton nextButton;

    public FirstCard(JPanel cp) 
    {
        this.contentPane = cp;
        initComponents();
    }

    private void initComponents() 
    {
        setOpaque(true);
        setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
        setBackground(Color.RED);
        setLayout(new BorderLayout(5, 5));

        nameLabel = new javax.swing.JLabel("Guarantee Name : ");
        nameField = new javax.swing.JTextField();   
        addLabel = new javax.swing.JLabel("Address : ");
        addField = new javax.swing.JTextField();        
        occLabel = new javax.swing.JLabel("Occupation : ");
        occField = new javax.swing.JTextField();
        phoneLabel = new javax.swing.JLabel("Phone : ");
        phoneField = new javax.swing.JTextField();
        centerPanel = new JPanel();
        nextButton = new JButton("Next");
        nextButton.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent ae)
            {
                nextButtonAction(ae);
            }
        });

        centerPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
        centerPanel.setOpaque(true);
        centerPanel.setBackground(Color.WHITE);
        centerPanel.setLayout(new GridLayout(0, 2, 5, 5));
        centerPanel.add(nameLabel);
        centerPanel.add(nameField);
        centerPanel.add(addLabel);
        centerPanel.add(addField);
        centerPanel.add(occLabel);
        centerPanel.add(occField);
        centerPanel.add(phoneLabel);
        centerPanel.add(phoneField);

        add(centerPanel, BorderLayout.CENTER);
        add(nextButton, BorderLayout.PAGE_END);
    }                   

    private void nextButtonAction(ActionEvent ae)
    {
        CardLayout layout = (CardLayout)contentPane.getLayout();
        layout.next(contentPane);
    }
}

class SecondCard extends javax.swing.JPanel 
{

    private javax.swing.JButton nextButton;
    private javax.swing.JLabel textLabel;
    private JPanel contentPane;

    public SecondCard(JPanel cp) 
    {
        contentPane = cp;
        initComponents();
    }

    private void initComponents() 
    {

        setOpaque(true);
        setBackground(Color.GREEN.darker().darker());
        setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
        textLabel = new JLabel("this is the second card", JLabel.CENTER);
        textLabel.setForeground(Color.WHITE);
        nextButton = new javax.swing.JButton();

        nextButton.setText("SwitchCard");
        nextButton.addActionListener(new ActionListener() 
        {
            public void actionPerformed(ActionEvent evt) 
            {
                jButton1ActionPerformed(evt);
            }
        });

        add(textLabel);
        add(nextButton);
    }

    private void jButton1ActionPerformed(ActionEvent evt) 
    {
        CardLayout layout = (CardLayout) contentPane.getLayout();
        layout.show(contentPane, "Panel 1");
    }
}

Method to clear fields

private void clearFields()
{
    Component components[] = centerPanel.getComponents();
    for (Component comp : components)
    {
        if (comp instanceof JTextField)
        {
            JTextField tfield = (JTextField) comp;
            tfield.setText("");
        }
        else if (comp instanceof JComboBox)
        {
            JComboBox cbox = (JComboBox) comp;
            cbox.setSelectedIndex(0);
        }
        else if (comp instanceof JRadioButton)
        {
            JRadioButton rbut = (JRadioButton) comp;
            rbut.setSelected(false);
        }
    }
}

And you will call this inside the actionPerformed() method of the Button, which will take you to the next Card.