Develop Reference

How to create multiple JPanels with JTextField input?

I am currently working on my school project to practice vocabulary, I have a method in my GUI that creates new vocabulary and the name of the list, I wanted to create a button that adds more Panels with input fields just this prototype image.
My idea is that when the user clicks
AddMoreButton it will add one JPanel just like P Panel, then the user can write vocabulary to send it to my database, is it possible to create something that?, I tried looping the P panel but it did not not change, any help would be appreciated.
private JPanel SetUpCreate() {
JPanel createPanel = new JPanel();
nameListInput = new JTextField(INPUT_FIELD_WIDTH);
termInput = new JTextField(INPUT_FIELD_WIDTH);
defintionInput = new JTextField(INPUT_FIELD_WIDTH);
p = new JPanel();
doneCreate = new JButton("Done");
doneCreate.addActionListener(new DoneCreateButtonAction());
addMoreButton = new JButton("Add");
addMoreButton.addActionListener(new AddMorePanelsListener());
p.setBorder(new BevelBorder(BevelBorder.RAISED));
p.add(termInput);
p.add(defintionInput);
JScrollPane pane = new JScrollPane(p);
createPanel.add(nameListInput);
createPanel.add(p);
createPanel.add(pane);
createPanel.add(doneCreate);
return createPanel;
}
private class DoneCreateButtonAction implements ActionListener {
public DoneCreateButtonAction() {
super();
}
public void actionPerformed(ActionEvent e) {
String namelist = nameListInput.getText();
String termglosa = termInput.getText();
String defintionglosa = defintionInput.getText();
try {
if (model.createWordList(namelist) && (model.createGlosa(termglosa, defintionglosa))) {
cl.show(cardPanel, "home");
}
} catch (IOException e1) {
JOptionPane.showMessageDialog(frame, "skapelsen av listan fungerar ej.");
}
}
}
private class AddMoreButtonAction implements ActionListener {
public AddMoreButtonAction() {
super();
}
public void actionPerformed(ActionEvent e) {
}
}

What I understand from your question is that you want to add another panel every time the user clicks the Add button and the panel to add contains fields for entering a word and its definition.
I see JScrollPane appears in the code you posted in your question. I think this is the correct implementation. In the below code, every time the user clicks the Add button I create a panel that contains the fields for a single word definition. This newly created panel is added to an existing panel that uses GridLayout with one column. Hence every time a new word definition panel is added, it is placed directly below the last word panel that was added and this GridLayout panel is placed inside a JScrollPane. Hence every time a word definition panel is added, the GridLayout panel height increases and the JScrollPane adjusts accordingly.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.WindowConstants;
public class MorPanel implements ActionListener, Runnable {
private static final String ADD = "Add";
private JFrame frame;
private JPanel vocabularyPanel;
#Override
public void run() {
showGui();
}
#Override
public void actionPerformed(ActionEvent actionEvent) {
String actionCommand = actionEvent.getActionCommand();
switch (actionCommand) {
case ADD:
vocabularyPanel.add(createWordPanel());
vocabularyPanel.revalidate();
vocabularyPanel.repaint();
break;
default:
JOptionPane.showMessageDialog(frame,
actionCommand,
"Unhandled",
JOptionPane.ERROR_MESSAGE);
}
}
public JButton createButton(String text) {
JButton button = new JButton(text);
button.addActionListener(this);
return button;
}
public JPanel createButtonsPanel() {
JPanel buttonsPanel = new JPanel();
buttonsPanel.add(createButton(ADD));
return buttonsPanel;
}
private JScrollPane createMainPanel() {
vocabularyPanel = new JPanel(new GridLayout(0, 1));
vocabularyPanel.add(createWordPanel());
JScrollPane scrollPane = new JScrollPane(vocabularyPanel);
return scrollPane;
}
private JPanel createWordPanel() {
JPanel wordPanel = new JPanel();
JLabel wordLabel = new JLabel("Enter Term");
JTextField wordTextField = new JTextField(10);
JLabel definitionLabel = new JLabel("Enter Term Definition");
JTextField definitionTextField = new JTextField(10);
wordPanel.add(wordLabel);
wordPanel.add(wordTextField);
wordPanel.add(definitionLabel);
wordPanel.add(definitionTextField);
return wordPanel;
}
private void showGui() {
frame = new JFrame("Vocabulary");
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.add(createButtonsPanel(), BorderLayout.PAGE_END);
frame.setSize(480, 200);
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new MorPanel());
}
}

As your code is not an Minimal Reproducible Example, I cannot provide further assistance than this:
Red part: Your main JPanel with BoxLayout
Green part: another JPanel with your JTextField in it.
Purple part: JScrollPane
Blue parts: custom JPanels with 2 panes in them, one on top for the number, one on the bottom for both JTextFields and icon, so I would say GridBagLayout or BoxLayout + FlowLayout
Orange part: JPanel with GridBagLayout or FlowLayout
Each time you clic on the + icon, you just create a new instance of the custom blue JPanel and that's it.

java swing it doesn't without system.out.println

Hello so i started learning java a week back and i basically started making a gui just to see how things work and i found a weird "bug" or i don't exactly understand how things work and it's not even a bug
i have a class called startPanel that makes a panel that is visible from the start
and it asks you as to what you wish to log in admin,user or a guest
this is startPanel:
package library;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/*
* this panel is responsible for the first opening panel and redirects you to your panel
*
*
*/
import javax.swing.*;
public class startPanel extends JFrame {
boolean adminState=false;
boolean userState=false;
boolean guestState=false;
JButton adminBut,userBut,guestBut ;
//start of constructor
public startPanel(){
//frame size,close when pressing x,title,and spawn at middle of the screen
this.setSize(500,500);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setTitle("Welcome guest");
this.setLocationRelativeTo(null);
//making the panel
JPanel panel1 = new JPanel();
//making a label to fill things up it doesn't really do anything
JLabel startLabel = new JLabel("you wan't to log in as...");
//3 buttons for the user to click 1 only and the according frame will show up
adminBut = new JButton("Admin");
userBut = new JButton("User");
guestBut = new JButton("Guest");
//making an event handler for admin only so far just for test purposes
ListenForButton lForButton = new ListenForButton();
adminBut.addActionListener(lForButton);
//adding comps to the panel
panel1.add(startLabel);
panel1.add(adminBut);
panel1.add(userBut);
panel1.add(guestBut);
//adding the panel to the frame
this.add(panel1);
} // end of startPanel constructor
private class ListenForButton implements ActionListener {
#Override
public void actionPerformed(ActionEvent event) {
/*probably not the correct way to do what i want to but just figured this might work
*it only works for admin button if the user presses the adminBut
*it will change the states and with a getter we can change each state
*from main accordingly
*/
if (event.getSource() == adminBut ){
adminState=true;
guestState=false;
userState= false;
}
}
} // end of Listen for button
//all getters for the states
public boolean getAdminState(){
return adminState;
}
public boolean getUserState(){
return guestState;
}
public boolean getGuestState(){
return userState;
}
}
this is main :
package library;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class mainLibrary {
public static void main(String[] args) {
adminPanel adminP = new adminPanel();
userPanel userP = new userPanel();
startPanel gui = new startPanel();
gui.setVisible(true);
while(true){
System.out.println(gui.getAdminState());
if (gui.getAdminState() == true) {
gui.setVisible(false);
userP.setVisible(true);
}
}
the problem now is that if i remove System.out.println(gui.getAdminState());
this does not work it doesn't even get in the if at all if it's false at start
if i don't remove it works correctly :/
so what is going on
this is adminPanel for the adminPanel if it matters
package library;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class adminPanel extends JFrame {
//start of adminPanel constructor
public adminPanel(){
//frame size,close when pressing x,title,and spawn at middle of the screen
this.setSize(500,500);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setTitle("Admin panel area");
this.setLocationRelativeTo(null);
JPanel panel1 = new JPanel();
this.add(panel1);
} //end of admin constructor
}

This is not a good GUI design. Never use such active loop.
Remarks: use standard naming convention (uppercase/lowercase), and never call a frame a panel (this is too confusing).
A better design would be to have references to Panels to be activated in the startPanel and setting appropriate property reacting to button actions. Something like:
class StartFrame extends JFrame implements ActionListener {
private JFrame adminFrame;
private JFrame userFrame;
...
// add construtor to initialize adminFrame and userFrame appropriately
...
public void actionPerformed(ActionEvent e) {
if (e.getSource() == adminBut) {
this.setVisible(false);
adminFrame.setVisible(true);
}
if (e.getSource() == userBut) {
this.setVisible(false);
userFrame.setVisible(true);
}
}
}

Swing: JTextField inside JPanel, redraw issue

I have recently started working with Java+Swing building an UI and I currently have an issue with JTextField placed on JPanel with FlowLayout.
In my example I have a window, containing panel with button. Clicking the button adds a component derived from JPanel and containing JTextField.
The problem is that when I type in JTextField it does not get updated (does not get resized). However when I resize the window or do anything else which forces window/panel redraw, the text field being resized (just what I expect to happen automatically).
When I change base class from JPanel to JTextField it works in the way I try to achieve, but I need to have JPanel as the base class so that I can take advantages of putting child components to it.
I have checked different questions here as well as I have Googled trying to find the solution, however it did not work for me. I have tried validate/invalidate/revalidate/repaint in different combinations and for different components, as well as trying to enforce revalidation for each typed character, which does not sound as the right way for me. So far I understoon that it is something to do with Layout Managers.
Could anyone please help me with understanding how that works and what should I read about how Swing UI, layout management and redrawing is working?
Also, I would be glad if someone could help me with my particular issue with my code.
Thanks in advance!
Here is my code below:
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
class TagVisual extends JPanel /*JTextField*/ {
private JTextField editField;
public TagVisual() {
FlowLayout layout = new FlowLayout();
layout.setHgap(0);
layout.setVgap(0);
setLayout(layout);
editField = new JTextField();
editField.setBackground(Color.RED);
editField.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
editField.setSize(editField.getSize());
editField.revalidate();
remove(editField);
add(editField);
revalidate();
repaint();
}
});
add(editField, FlowLayout.LEFT);
}
public void place(JPanel panel) {
panel.add(this);
editField.grabFocus();
}
}
public class MainWindow {
private JPanel mainPanel;
private JButton btnPlace;
private JFrame frame;
public MainWindow(JFrame frame) {
mainPanel = new JPanel(new FlowLayout());
btnPlace = new JButton();
btnPlace.setText("Place");
mainPanel.add(btnPlace);
this.frame = frame;
btnPlace.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
TagVisual v = new TagVisual();
v.place(mainPanel);
mainPanel.revalidate();
mainPanel.repaint();
mainPanel.updateUI();
frame.revalidate();
frame.repaint();
}
});
}
public static void main(String[] args) {
JFrame frame = new JFrame("TextFieldUpdateIssue");
frame.setContentPane(new MainWindow(frame).mainPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
}

If i were you, i would not try to resize the textfields when the user enters some text.
I suggest you to give them a fixed size using JTextField (int columns) constructor, this will allow you to create some textfields which are "wide enough".
If you still want to make them wider when some text is entered, you can't use an ActionListener, since it will fire an event when the user presses ENTER key, not based on the text entered.
For this purpose you can register a Document Listener on your textfield's document.
You also could override getPreferredSize () method to calculate and return an appropriate size. In the example below i use a JLabel for convenience to calculate the preferred width, but you could use FontMetrics.
If you are adding multiple tags to your panel, you should also consider using a JScrollPane in order to make scrollbars appear when your panel needs more space.
See this example (i changed a bit your code because it would not compile and the general design was bad, now i think it is better, but not still good) :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class MainWindow
{
public static void main (String [] a) {
SwingUtilities.invokeLater (new Runnable () {
#Override public void run () {
try {
UIManager.setLookAndFeel (UIManager.getSystemLookAndFeelClassName ());
createAndShowGUI ();
}
catch (Exception e) {
JOptionPane.showMessageDialog (null, "An unexpected error occurred: " + e.getClass ().getSimpleName (), "Error", JOptionPane.ERROR_MESSAGE);
}
}
});
}
private static void createAndShowGUI () {
JFrame frame = new JFrame ("TextFieldUpdateIssue");
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
frame.setContentPane (new MainPanel ());
frame.setExtendedState (JFrame.MAXIMIZED_BOTH);
frame.setLocationRelativeTo (null);
frame.setVisible (true);
}
}
class MainPanel extends JPanel
{
private JPanel tagsPanel;
public MainPanel () {
super (new BorderLayout (0, 10));
add (new JButton (new AbstractAction ("Add tag") {
#Override public void actionPerformed(ActionEvent e) {
addNewTag ();
}
}), BorderLayout.NORTH);
tagsPanel = new JPanel ();
tagsPanel.setLayout (new FlowLayout (FlowLayout.CENTER, 10, 0));
add (tagsPanel, BorderLayout.CENTER);
}
private void addNewTag () {
TagVisual v = new TagVisual ();
tagsPanel.add (v);
v.grabFocusOnField ();
revalidate ();
}
}
class TagVisual extends JPanel
{
private JTextField editField;
public TagVisual() {
super (new FlowLayout (FlowLayout.CENTER, 0, 0));
add (editField = createNewTextField (null), FlowLayout.LEFT);
}
private JTextField createNewTextField (String text) {
JTextField textField = new JTextField (text) {
#Override public Dimension getPreferredSize () {
Dimension d = super.getPreferredSize ();
return new Dimension (new JLabel (getText ()).getPreferredSize ().width + 10, d.height);
}
};
textField.setBackground (Color.RED);
textField.getDocument ().addDocumentListener (new DocumentListener () {
#Override public void changedUpdate (DocumentEvent e) {
revalidate ();
}
#Override public void insertUpdate (DocumentEvent e) {
revalidate ();
}
#Override public void removeUpdate (DocumentEvent e) {
revalidate ();
}
});
return textField;
}
public void grabFocusOnField () {
editField.grabFocus ();
editField.setCaretPosition (editField.getText ().length ());
}
}
Screenshot (short text):
Screenshot (Longer text):

Please review the code and note comments:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class MainWindow {
private JPanel mainPanel;
private JButton btnPlace;
public MainWindow(){
JFrame frame = new JFrame("TextFieldUpdateIssue");
//you can't use components before initializing them
btnPlace = new JButton("Button");
frame.add(btnPlace, BorderLayout.NORTH);
mainPanel = new JPanel();
frame.add(mainPanel, BorderLayout.CENTER);
btnPlace.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
TagVisual v = new TagVisual();
mainPanel.add(v); //add it to main panel
//v.place(mainPanel);
//mainPanel.revalidate();
//mainPanel.repaint();
//mainPanel.updateUI();
//frame.revalidate();
//frame.repaint();
frame.pack();
}
});
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
new MainWindow();
}
}
class TagVisual extends JPanel /*JTextField*/ {
private JTextField editField;
public TagVisual() {
FlowLayout layout = new FlowLayout();
layout.setHgap(0);
layout.setVgap(0);
setLayout(layout);
editField = new JTextField();
//give it a preferred size to be used by layout manager
editField.setPreferredSize(new Dimension(150,25));
editField.setBackground(Color.RED);
editField.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
//not sure what you want to do here
//not relevant to the question
}
});
add(editField, FlowLayout.LEFT);
}
}

Adding graphics into a JFrame using BorderLayout

I'm trying to do a simple piece of homework, where I display a line of text displaying whether a door object is open or not. Underneath that, I visually represent it (using the drawRect) method. And at the bottom I have two buttons, which can open or close the door, thus changing the text and rectangle.
Edit: List of code that can be compiled given now:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Test {
public static void main(String[] args) {
// Creates new JFrame called frame, with title "Door"
// (displayed at top of screen).
JFrame frame = new JFrame ("Door");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
TempDoorPanel panel = new TempDoorPanel();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
}
class Door {
private String state;
private String message;
Door (String state) {
this.state = state;
message = "The door is currently closed.";
}
public boolean isOpen() {
return state.equals ("open");
}
public boolean isClosed() {
return state.equals ("closed");
}
public void setState(String state) {
this.state = state;
}
public String getMessage() {
return message;
}
public void open() {
if (state.equals("open")) {
message = "The door is already open.";
}
else {
state = "open";
message = "The door has been opened.";
}
}
public void drawOpenDoor (Graphics page) {
page.drawRect(100, 100, 100, 100);
}
}
class TempDoorPanel extends JPanel {
private Door door;
private JTextField currentStateOfDoor;
private JButton openDoor;
public TempDoorPanel() {
super.setLayout(new BorderLayout());
door = new Door("closed");
super.setBackground(Color.blue);
super.setPreferredSize(new Dimension (360, 400));
currentStateOfDoor = new JTextField(14);
currentStateOfDoor.setText(door.getMessage());
super.add(currentStateOfDoor, BorderLayout.NORTH);
openDoor = new JButton("Open Door");
class openDoorListener implements ActionListener {
public void actionPerformed (ActionEvent event) {
door.open();
repaintText();
}
}
openDoorListener openlistener = new openDoorListener();
openDoor.addActionListener(openlistener);
JPanel holder = new JPanel();
holder.add(openDoor);
super.add(holder, BorderLayout.SOUTH);
}
private void repaintText() {
currentStateOfDoor.setText(door.getMessage());
// These methods are from Door class.
}
public void paintComponent (Graphics page) {
super.paintComponent(page);
if (door.isOpen())
door.drawOpenDoor(page);
// isOpen is a boolean method from Door class.
}
}
What works:
Buttons appear at right place on screen, at BorderLayout.SOUTH, one after the other.
The JTextField appears at right place, at BorderLayout.NORTH
Finally, the blue area appears in the right place in the centre of the screen.
What I'm trying to fix:
I have no idea how to display the rectangle properly in the middle of that blue area. I've tried changing the coordinates and size of the rectangle, which doesn't change the size of it at all. I can make it drawRect(100, 100, 100, 100) and it changes nothing.
I'm also aware that the rectangle is currently hidden behind the top left corner of the JTextField, but I can't figure out how to move it into the BorderLayout.
Questions:
How do you place a rectangle in a BorderLayout?
How do you adjust the size of a rectangle, drawn via drawrect(), in such a layout?

Because you add components to the JPanel you draw on the JTextField is covering your drawing.
Solution:
1) Either compensate for this by checking the JTextField height in your drawRect(..) method
or better
2) Dont add components to the same JPanel which you are drawing on unless it cant be helped.
So basically I made your TempDoorPanel add a new JPanel to BorderLayout.CENTER which is the drawing panel we can now use drawRect(0,0,10,10) and it will show in the top left hand corner of JPanel drawingPanel.
Also dont call setPreferredSize on JPanel rather override getPreferredSize() and return Dimensions which fit your drawings.
To invoke paintComponent outside of the class simply call repaint() its instance
See this example which uses point no.2:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class Test {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame("Door");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
TempDoorPanel panel = new TempDoorPanel();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
});
}
}
class Door {
private String state;
private String message;
public Door(String state) {
this.state = state;
message = "The door is currently closed.";
}
public void drawOpenDoor(Graphics page) {
page.setColor(Color.GREEN);
page.drawRect(0, 0, 10, 10);
}
}
class TempDoorPanel extends JPanel {
private Door door;
private JTextField currentStateOfDoor;
private JButton openDoor;
public TempDoorPanel() {
super.setLayout(new BorderLayout());
door = new Door("closed");
currentStateOfDoor = new JTextField(14);
//AcurrentStateOfDoor.setText(door.getMessage());
super.add(currentStateOfDoor, BorderLayout.NORTH);
openDoor = new JButton("Open Door");
final JPanel drawingPanel = new JPanel() {
#Override
protected void paintComponent(Graphics grphcs) {
super.paintComponent(grphcs);
// if (door.isOpen()) {
door.drawOpenDoor(grphcs);
// }
// isOpen is a boolean method from Door class.
}
};
drawingPanel.setBackground(Color.blue);
add(drawingPanel);
class openDoorListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
//door.open();
repaintText();
drawingPanel.repaint();//so paint component of drawing panel is called
}
}
openDoorListener openlistener = new openDoorListener();
openDoor.addActionListener(openlistener);
JPanel holder = new JPanel();
holder.add(openDoor);
super.add(holder, BorderLayout.SOUTH);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
private void repaintText() {
// currentStateOfDoor.setText(door.getMessage());
// These methods are from Door class.
}
}

When you handler the door opening event with your listener;
class openDoorListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
door.open();
repaintText();
}
}
you don't actually include a call to repaint the panel; hence the panel's paintComponent() method isn't called and door.drawOpenDoor() isn't called. You can test this by clicking the button and then resizing the frame. When you resize, the panel is automatically repainted and bingo, your door appears.
You can fix this by adding a call to repaint() in your ActionListener;
class openDoorListener implements ActionListener {
public void actionPerformed(ActionEvent event) {
door.open();
repaintText();
repaint(); // requests that the panel be repainted
}
}

Java Swing add/remove jButtons on runtime

My application has a module which allows the user to add jButtons on the jLayeredpane during runtime. I want to add action listeners to this dynamically added contents and also i have to provide access to delete the dynamically added buttons during runtime. Is there any way to do this ?
private Map<String, JButton> dynamicButtons;
public void addButton(String name) {
JButton b = new JButton(name);
b.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jLayeredPane2.add(b);
dynamicButtons.put(name, b);
jLayeredPane2.invalidate();
}
public void removeButton(String name) {
JButton b = dynamicButtons.remove(name);
jLayeredPane2.remove(b);
jLayeredPane2.invalidate();
}

Original Answer Good in general, but done differently in this case
In order to keep track of an arbitrary number of added JButtons, you will need to keep them in a list.
So, after you create a new button, add the listeners to it, and add it to the pane, you then need to save that new button in a list.
That way you can keep track of all of the buttons you have added.
You could also use a Map<String, JButton> that maps a button name to the button.
Example:
private Map<String, JButton> dynamicButtons;
public void addButton(String name) {
JButton b = new JButton(name);
b.addActionListener(someAction);
yourPanel.add(b);
dynamicButtons.put(name, b);
yourPanel.invalidate();
}
public void removeButton(String name) {
Button b = dynamicButtons.remove(name);
yourPanel.remove(b);
yourPanel.invalidate();
}
The following is a full class that lets you add and remove buttons dynamically. It's not exactly what you want, but it should get you really close.
Code for your specific case:
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class ExampleFrame extends JFrame {
private JButton add, remove;
private JPanel dynamicButtonPane, addRemovePane;
private boolean waitingForLocationClick;
public ExampleFrame() {
super("Dynamic button example");
waitingForLocationClick = false;
add = new JButton("Add Button");
add.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
addButton(JOptionPane
.showInputDialog("Name of the new button:"));
}
});
remove = new JButton("Remove Button");
remove.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
lookingToRemove = true;
}
});
JPanel mainPane = new JPanel(new BorderLayout());
dynamicButtonPane = new JPanel();
dynamicButtonPane.setLayout(null);
dynamicButtonPane.setPreferredSize(new Dimension(300, 300));
addRemovePane = new JPanel();
addRemovePane.add(add);
addRemovePane.add(remove);
mainPane.add(dynamicButtonPane, BorderLayout.NORTH);
mainPane.add(addRemovePane, BorderLayout.SOUTH);
add(mainPane);
pack();
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
dynamicButtonPane.addMouseListener(pointSelectorListener);
}
private JButton buttonToPlace;
public void addButton(String name) {
JButton b = new JButton(name);
b.setActionCommand(name);
b.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (lookingToRemove) {
if (e.getSource() instanceof JButton) {
dynamicButtonPane.remove((Component) e.getSource());
dynamicButtonPane.validate();
dynamicButtonPane.repaint();
}
} else
JOptionPane.showMessageDialog(ExampleFrame.this, "This is " + e.getActionCommand());
}
});
waitingForLocationClick = true;
lookingToRemove = false;
buttonToPlace = b;
}
public void putButtonAtPoint(Point p) {
System.out.println("Placing a button at: " + p.toString());
dynamicButtonPane.add(buttonToPlace);
buttonToPlace.setBounds(new Rectangle(p, buttonToPlace
.getPreferredSize()));
dynamicButtonPane.validate();
buttonToPlace = null;
waitingForLocationClick = false;
}
private boolean lookingToRemove = false;
private final MouseListener pointSelectorListener = new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
if (waitingForLocationClick) {
putButtonAtPoint(e.getPoint());
} else {
System.out.println("Not in waiting state");
}
}
};
public static void main(String[] args) {
new ExampleFrame();
}
}

Absolutely. All of this stuff can be done programatically at any time. Here are a couple of hints to avoid problems and pitfalls:
When you add components to any panel, make sure this is done on the Event Dispatch Thread through SwingUtilities.invokeLater(Runnable). Inside the Runnable, you want to add the component to the panel, hook up the listeners, and re-layout the panel.
Use SwingUtilities.isEventDispatchThread() to check to see if you are already on the event dispatch thread. If you are, then you can just run the Runnable immediately instead of calling invokeLater.
Once you've modified the layout of a panel, be sure to call Component.invalidate() on the panel to make sure it gets laid out again.
Maintain your own list of listeners. Overwrite the add and remove methods on the panel to add or remove them from your list and also from all existing buttons. When you add new buttons, add all listeners on the list.
This is a very common task, and it is fully supported by Java. You should be able to get it done without too much trouble.