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How to add an JPanel from an other class to an existing Frame

I have my MainWindow class where menue buttons and everything else are. In the middle of it is an Panel called content. I want to load JPanels from other classes into this field. But when i start the code below nothing shows up.
MainWindow Class:
public class MainWindow {
private JFrame frame;
private JScrollPane Content;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MainWindow window = new MainWindow();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public MainWindow() {
initialize();
}
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JScrollPane scrollPane = new JScrollPane();
frame.getContentPane().add(scrollPane, BorderLayout.CENTER);
JPanel TopPanel = new JPanel();
scrollPane.setColumnHeaderView(TopPanel);
JLabel lblNewLabel = new JLabel("Made by " + Globals.Author);
TopPanel.add(lblNewLabel);
JButton btnHome = new JButton("Home");
TopPanel.add(btnHome);
btnHome.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
Content.add(new Home());
}
});
Content = new JScrollPane();
scrollPane.setViewportView(Content);
}
}
JPanel Class:
public class Home extends JPanelContentTemplate {
/**
* Create the panel.
*/
protected void InitializeComponents(){
setLayout(new BorderLayout(0, 0));
JPanel OptionsMenuePanel = new JPanel();
add(OptionsMenuePanel, BorderLayout.WEST);
JPanel ConentPanel = new JPanel();
add(ConentPanel, BorderLayout.CENTER);
ConentPanel.setLayout(new GridLayout(1, 2, 0, 0));
JLabel lblConnectedWith = new JLabel("Connected With:");
ConentPanel.add(lblConnectedWith);
JTextPane textServerIP = new JTextPane();
ConentPanel.add(textServerIP);
}
#Override
protected void Refresh() {
// TODO Auto-generated method stub
}
}
The InitializeComponents method comes from an Self Created Superclass:
public abstract class JPanelContentTemplate extends JPanel {
/**
* Create the panel.
*/
public JPanelContentTemplate() {
InitializeComponents();
}
protected abstract void InitializeComponents();
protected abstract void Refresh();
}
I also tried an repaint etc.
Thanks for Help

Nothing shows up because you add nothing but empty JScrollPanes to your GUI:
Content = new JScrollPane();
scrollPane.setViewportView(Content);

Here is a simple example of adding separate panels to the MainFrame. I hope it helps you.
public class SidePanel extends JPanel {
private JLabel label;
public SidePanel() {
setBorder(BorderFactory.createEtchedBorder());
label = new JLabel("Hello");
setVisible(true);
/* More Code Goes Here */
}
}
public class CenterPanel extends JPanel {
/* Center Panel Code */
}
public class MainFrame extends JFrame {
private SidePanel sidePanel;
private CenterPanel centerPanel;
public MainFrame() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
sidePanel = new SidePanel();
centerPanel = new CenterPanel();
add(sidePanel, BorderLayout.WEST);
add(centerPanel, BorderLayout.CENTER);
setSize(300, 300);
setVisible(true);
}
}
/* Main App */
public static void main(String [] args) {
try {
/* Lambda Expression */
SwingUtitlities.InvokeLater(() -> new MainFrame());
} catch(Exception ex) {
ex.printStackTrace();
}
}

JTextField and button is not updated while switching between panel using cardlayout

I have been struggling with updating Jtextfield and Jbutton data in cardlayout from couple of days. I have created small demo to explain my problem.. When I click on "start" button it should show another panel and thats is working but when I return back to main page I want my Jtextfield and jbutton to be updated from "world" to "hello" but that is not working. Any help and suggestions would be appreciated.(Sorry about the indentation of code, I do not know why copy-paste did not work properly).
public class CardlayoutDemo {
public static String data = "world";
private static final String INTRO = "intro";
private static final String GAME = "game";
private CardLayout cardlayout = new CardLayout();
private JPanel mainPanel = new JPanel(cardlayout);
private IntroPanel introPanel = new IntroPanel();
private GamePanel gamePanel = new GamePanel();
public CardlayoutDemo() {
mainPanel.add(introPanel.getMainComponent(), INTRO);
mainPanel.add(gamePanel.getMainComponent(), GAME);
introPanel.addBazBtnActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
CardlayoutDemo.data = "hello";
mainPanel.repaint();
mainPanel.revalidate();
CardLayout cl = (CardLayout)mainPanel.getLayout();
cl.show(mainPanel, GAME);
}
});
gamePanel.addBackBtnActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
CardLayout cl = (CardLayout)mainPanel.getLayout();
cl.show(mainPanel, INTRO);
}
});
}
private JComponent getMainComponent() {
return mainPanel;
}
private static void createAndShowUI() {
JFrame frame = new JFrame("Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new CardlayoutDemo().getMainComponent());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}
class IntroPanel {
private JPanel mainPanel = new JPanel();
public JButton start;
private JButton exit;
private JTextField lblData;
public IntroPanel() {
mainPanel.setLayout(new BorderLayout());
JPanel content = new JPanel();
start = new JButton("Start");
exit = new JButton(CardlayoutDemo.data);
lblData = new JTextField(CardlayoutDemo.data);
content.add(lblData);
content.add(start);
content.add(exit);
mainPanel.add(content, BorderLayout.CENTER);
exit.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Window win = SwingUtilities.getWindowAncestor(mainPanel);
win.dispose();
}
});
}
public void addBazBtnActionListener(ActionListener listener) {
start.addActionListener(listener);
}
public JComponent getMainComponent() {
return mainPanel;
}
}
class GamePanel {
private static final Dimension MAIN_SIZE = new Dimension(400, 200);
private JPanel mainPanel = new JPanel();
private JButton back;
public GamePanel() {
back = new JButton("return to main menu");
mainPanel.add(back);
mainPanel.setPreferredSize(MAIN_SIZE);
}
public JComponent getMainComponent() {
return mainPanel;
}
public void addBackBtnActionListener(ActionListener listener) {
back.addActionListener(listener);
}
}

when this line gets executed inside your listener:
CardlayoutDemo.data = "hello";
You´re creating a new java.lang.String object and setting the field data to reference the new String you have just created. This has no effect over the internal state of the JTextField or the String object which was previously referenced by the variable.
To change the text of the JTextField you should call the setText(String) method of JTextField .

No, don't override the show method. Instead give your classes methods that allow other classes the ability to change their state. For instance, you could add this method to the IntroPanel class:
class IntroPanel {
// .....
// !! added!
public void lblDataSetText(String text) {
lblData.setText(text);
}
}
and then call it when you want to change the state of its lblData field:
introPanel.addBazBtnActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// !! CardlayoutDemo.data = "hello";
mainPanel.repaint();
mainPanel.revalidate();
CardLayout cl = (CardLayout) mainPanel.getLayout();
cl.show(mainPanel, GAME);
introPanel.lblDataSetText("Hello!"); // !!
}
});
Note that this is a quick and dirty solution. If you want a more robust solution that scales better in larger programs, then re-structure your program along an M-V-C design pattern, and have your view change the displayed text in response to a change in the state of a String in the model. This would require more work, and in a small "toy" program wouldn't be worth the effort, but in a large complex program is well worth the effort since it would help reduce coupling and thereby reduce complexity and risk of bugs.

Can't display index of selected list value inside a JPanel

I have a list and I want each time when I select a value from the list, its index to be displayed into a JPanel. I must mention that when I print the index in the console it gets printed the right way, but in the JPanel I don't get anything. An very intresting that I noticed is that in first instance if I select a value nothing is displayed in the JPanel, but if I minimize the frame and then maximize it back the index is displayed in the panel.
Any explanations for this strange behaviour?
public class Start extends JFrame {
private static JPanel leftPanel = new JPanel();
private static JPanel rightPanel = new JPanel();
private JList leftList = new JList();
private DefaultListModel<String> listModel = new DefaultListModel<String>();
private static JScrollPane listScrollPane;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
new Start();
JFrame frame = new JFrame();
frame.add(leftPanel,BorderLayout.EAST);
frame.add(listScrollPane,BorderLayout.WEST);
frame.add(rightPanel);
frame.setTitle("Example");
frame.setSize(600,400);
frame.setLocation(200,100);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public Start() {
leftPanel.setLayout(new BoxLayout(leftPanel,BoxLayout.PAGE_AXIS));
leftList = new JList(listModel);
leftList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
listScrollPane = new JScrollPane(leftList);
listScrollPane.setBorder(BorderFactory.createTitledBorder("Proteins"));
rightPanel.setBackground(Color.cyan);
rightPanel.setLayout(new FlowLayout());
for (String name : allNames) {
listModel.addElement(name);
}
leftList.addListSelectionListener(new ListSelectionListener() {
#Override
public void valueChanged(ListSelectionEvent event) {
if(!event.getValueIsAdjusting()) {
int indexndex = leftList.getSelectedIndex();
JLabel lbl = new JLabel();
lbl.setText("index = " + index);
rightPanel.add(lbl);
System.out.println(index);
}
}
});
}
}

Table does not update when selecting combobox

My problem is that a JTable does not update when I select my combobox. The program I present below should delete all data (data = null;), when LA is selected. The table does not update.
public class minimumExample extends JFrame {
private JTabbedPane tabbedPane;
private FilteredTabPanel filteredTabPanel;
public void createTabBar() {
tabbedPane = new JTabbedPane(JTabbedPane.TOP);
filteredTabPanel = new FilteredTabPanel();
tabbedPane.addTab("Test", filteredTabPanel.createLayout());
add(tabbedPane);
tabbedPane.setTabLayoutPolicy(JTabbedPane.SCROLL_TAB_LAYOUT);
}
private void makeLayout() {
setTitle("Test App");
setLayout(new BorderLayout());
setPreferredSize(new Dimension(1000, 500));
createTabBar();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setVisible(true);
}
public void start() {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
makeLayout();
}
});
}
public static void main(String[] args) throws IOException {
minimumExample ex = new minimumExample();
ex.start();
}
public class FilteredTabPanel extends JPanel {
private JPanel selectionArea;
private JLabel lCity;
private JComboBox cityBox;
private JTable filterTable;
String[] columnNames = {"Cities"};
String[][] data = {
{"NY"}, {"NY"}, {"NY"}, {"NY"}, {"LA"}, {"LA"},{"Columbia"},{"DC"},{"DC"},{"DC"},{"DC"},{"DC"},{"DC"}
};
private JScrollPane scrollPane;
public JPanel createLayout() {
JPanel panel = new JPanel(new GridLayout(0, 1));
//add panels to the layout
panel.add(addButtons());
panel.add(showTable());
repaint();
revalidate();
return panel;
}
public JPanel addButtons(){
selectionArea = new JPanel(new FlowLayout(FlowLayout.LEFT));
lCity = new JLabel("City");
String[] fillings = {"NY", "LA", "Columbia", "DC"};
cityBox = new JComboBox(fillings);
cityBox.addActionListener(new ActionListener() {
private String cityFilter;
#Override
public void actionPerformed(ActionEvent arg0) {
//2. get data
cityFilter = cityBox.getSelectedItem().toString();
if(cityFilter.equals("LA")) {
data = null;
}
showTable();
repaint();
}
});
selectionArea.add(lCity);
selectionArea.add(cityBox);
selectionArea.repaint();
return selectionArea;
}
private JScrollPane showTable() {
filterTable =new JTable(data, columnNames);
filterTable.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
scrollPane = new JScrollPane(filterTable);
scrollPane.repaint();
scrollPane.validate();
return scrollPane;
}
}
}
As you can see the table does not update. Any recommendations what I am doing wrong?

Instead of creating new instance of you objects by calling showTable (which never get added to the screen in any way), which is just going to completely mess up your object references, try resetting the TableModel, for example...
if ("LA".equals(cityFilter)) {
filterTable.setModel(new DefaultTableModel(null, columnNames));
}
Take a closer look at How to Use Tables for more details

Adding JPanels from other classes to the cardLayout

I've got 3 windows in 3 separate classes and I would like to use cardLayout so that when you click the next button, the next window will appear. How do I add JPanels containing different elements to one cardLayout? This is the first window: (the only difference is the background though - but it represents the idea of how I got it actually)
public class Window1 extends JPanel implements ActionListener {
static CardLayout cardLayout = new CardLayout();
public Window1() {
init();
}
private void init() {
JPanel jp = new JPanel(new BorderLayout());
JPanel jp2 = new Window2();
//JPanel jp3 = new Window3();
JLabel textLabel = new JLabel("Window1");
jp.setBackground(Color.GREEN);
jp.add(textLabel, BorderLayout.CENTER);
JButton nextButton = new JButton("NEXT");
nextButton.setActionCommand("next");
nextButton.addActionListener(this);
jp.add(nextButton, BorderLayout.EAST);
setLayout(cardLayout);
add(jp, "string");
add(jp2, "string");
//add(jp3, "string");
}
public void actionPerformed(ActionEvent e) {
if (e.getActionCommand().equalsIgnoreCase("next")) {
// go to the next window
cardLayout.next(this);
}
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("test");
frame.getContentPane().setLayout(Window1.cardLayout);
frame.getContentPane().add(new Window1(), "Center");
frame.getContentPane().add(new Window2(), "Center");
frame.getContentPane().add(new Window3(), "Center");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(550, 450);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
The second window:
public class Window2 extends JPanel implements ActionListener {
//static CardLayout cardLayout = new CardLayout();
public Window2() {
init();
}
private void init() {
setLayout(new BorderLayout());
JLabel textLabel = new JLabel("Window2");
setBackground(Color.RED);
add(textLabel, BorderLayout.CENTER);
JButton nextButton = new JButton("NEXT");
nextButton.setActionCommand("next");
nextButton.addActionListener(this);
add(nextButton, BorderLayout.EAST);
//setLayout(cardLayout);
//JPanel jp3 = new Window3();
//add(jp3, "string");
}
public void actionPerformed(ActionEvent e) {
if (e.getActionCommand().equalsIgnoreCase("next")) {
// go to the next window??
System.out.println("window2");
Window1.cardLayout.next(this);
}
}
}
And the last one:
public class Window3 extends JPanel implements ActionListener {
public Window3() {
init();
}
private void init() {
setLayout(new BorderLayout());
JLabel textLabel = new JLabel("Window3");
setBackground(Color.BLUE);
add(textLabel, BorderLayout.CENTER);
JButton nextButton = new JButton("NEXT");
nextButton.setActionCommand("next");
nextButton.addActionListener(this);
add(nextButton, BorderLayout.EAST);
}
public void actionPerformed(ActionEvent e) {
if (e.getActionCommand().equalsIgnoreCase("next")) {
// go to the next window
// Window1.cardLayout.next(this);
}
}
}

I had made a small program, hopefully the comments written in the program, might be able to guide you, to understand how to use CardLayout.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/* Here we are first declaring our class that will act as the
* base for other panels or in other terms the base for CardLayout.
*/
public class CardLayoutTest
{
private static final String CARD_JBUTTON = "Card JButton";
private static final String CARD_JTEXTFIELD = "Card JTextField";
private static final String CARD_JRADIOBUTTON = "Card JRadioButton";
private static void createAndShowGUI()
{
JFrame frame = new JFrame("Card Layout Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
// This JPanel is the base for CardLayout for other JPanels.
final JPanel contentPane = new JPanel();
contentPane.setLayout(new CardLayout(20, 20));
/* Here we be making objects of the Window Series classes
* so that, each one of them can be added to the JPanel
* having CardLayout.
*/
Window1 win1 = new Window1();
contentPane.add(win1, CARD_JBUTTON);
Window2 win2 = new Window2();
contentPane.add(win2, CARD_JTEXTFIELD);
Window3 win3 = new Window3();
contentPane.add(win3, CARD_JRADIOBUTTON);
/* We need two JButtons to go to the next Card
* or come back to the previous Card, as and when
* desired by the User.
*/
JPanel buttonPanel = new JPanel();
final JButton previousButton = new JButton("PREVIOUS");
previousButton.setBackground(Color.BLACK);
previousButton.setForeground(Color.WHITE);
final JButton nextButton = new JButton("NEXT");
nextButton.setBackground(Color.RED);
nextButton.setForeground(Color.WHITE);
buttonPanel.add(previousButton);
buttonPanel.add(nextButton);
/* Adding the ActionListeners to the JButton,
* so that the user can see the next Card or
* come back to the previous Card, as desired.
*/
previousButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
CardLayout cardLayout = (CardLayout) contentPane.getLayout();
cardLayout.previous(contentPane);
}
});
nextButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
CardLayout cardLayout = (CardLayout) contentPane.getLayout();
cardLayout.next(contentPane);
}
});
// Adding the contentPane (JPanel) and buttonPanel to JFrame.
frame.add(contentPane, BorderLayout.CENTER);
frame.add(buttonPanel, BorderLayout.PAGE_END);
frame.pack();
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}
class Window1 extends JPanel
{
/*
* Here this is our first Card of CardLayout, which will
* be added to the contentPane object of JPanel, which
* has the LayoutManager set to CardLayout.
* This card consists of Two JButtons.
*/
private ActionListener action;
public Window1()
{
init();
}
private void init()
{
final JButton clickButton = new JButton("CLICK ME");
final JButton dontClickButton = new JButton("DON\'T CLICK ME");
action = new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
if (ae.getSource() == clickButton)
{
JOptionPane.showMessageDialog(null, "Hello there dude!"
, "Right Button", JOptionPane.INFORMATION_MESSAGE);
}
else if (ae.getSource() == dontClickButton)
{
JOptionPane.showMessageDialog(null, "I told you not to click me!"
, "Wrong Button", JOptionPane.PLAIN_MESSAGE);
}
}
};
clickButton.addActionListener(action);
dontClickButton.addActionListener(action);
add(clickButton);
add(dontClickButton);
}
}
class Window2 extends JPanel implements ActionListener
{
/*
* Here this is our second Card of CardLayout, which will
* be added to the contentPane object of JPanel, which
* has the LayoutManager set to CardLayout.
* This card consists of a JLabel and a JTextField
* with GridLayout.
*/
private JTextField textField;
public Window2()
{
init();
}
private void init()
{
setLayout(new GridLayout(1, 2));
JLabel userLabel = new JLabel("Your Name : ");
textField = new JTextField();
textField.addActionListener(this);
add(userLabel);
add(textField);
}
public void actionPerformed(ActionEvent e)
{
if (textField.getDocument().getLength() > 0)
JOptionPane.showMessageDialog(null, "Your Name is : " + textField.getText()
, "User\'s Name : ", JOptionPane.QUESTION_MESSAGE);
}
}
class Window3 extends JPanel
{
/*
* Here this is our third Card of CardLayout, which will
* be added to the contentPane object of JPanel, which
* has the LayoutManager set to CardLayout.
* This card consists of Two JLabels and two JCheckBox
* with GridLayout.
*/
private ActionListener state;
public Window3()
{
init();
}
public void init()
{
setLayout(new GridLayout(2, 2));
JLabel maleLabel = new JLabel("MALE", JLabel.CENTER);
final JCheckBox maleBox = new JCheckBox();
JLabel femaleLabel = new JLabel("FEMALE", JLabel.CENTER);
final JCheckBox femaleBox = new JCheckBox();
state = new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
if (maleBox == (JCheckBox) ae.getSource())
{
femaleBox.setSelected(false);
JOptionPane.showMessageDialog(null, "Congrats you are a Male"
, "Gender : ", JOptionPane.INFORMATION_MESSAGE);
}
else if (femaleBox == (JCheckBox) ae.getSource())
{
maleBox.setSelected(false);
JOptionPane.showMessageDialog(null, "Congrats you are a Female"
, "Gender : ", JOptionPane.INFORMATION_MESSAGE);
}
}
};
maleBox.addActionListener(state);
femaleBox.addActionListener(state);
add(maleLabel);
add(maleBox);
add(femaleLabel);
add(femaleBox);
}
}

There are a couple things:
As your program can only run 1 main method, each class doesnt need one, but whichever you do run should create an instance of each panel you want to add to your CardLayout.
You also do not seem to add your Windows to your CardLayout at all. You could try the following (uncomplied). This would only be needed in one class:
private static void createAndShowGUI() {
JFrame frame = new JFrame("test");
frame.getContentPane().setLayout(Window1.cardLayout);
frame.getContentPane().add(new Window1());
frame.getContentPane().add(new Window2());
frame.getContentPane().add(new Window3());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(550, 450);
frame.setVisible(true);
}
Further (and this might just be due to the simplicity of your example), I would just have 1 class, and it would take the name of the panel and the color of the background to the constructor. These could be passed into your init() method and your design would be somewhat streamlined.