Develop Reference

java swing remove latest added panel

I am adding panels to a frame with a button click, each panel goes under the last added panel, I achieve that with setBounds, each time incrementing y position. There is a second button, that is supposed to remove the latest panel that I added. It should keep removing panels after every click. I have tried a few solutions but they all failed.
My code:
public class lab3 {
static int y = 50;
static JButton addThread;
static JPanel results;
public static void main(String[] args) {
JFrame jFrame = new JFrame();
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setSize(550, 650);
jFrame.setTitle("Lab3");
jFrame.setVisible(true);
JPanel panelAddThread = new JPanel();
panelAddThread.setLayout(null);
panelAddThread.setBounds(0, 0, 550, 50);
panelAddThread.setBackground(Color.red);
JLabel threadLabel = new JLabel();
threadLabel.setText("Thread count: ");
addThread = new JButton();
addThread.setBounds(300, 0, 25, 25);
addThread.setText("+");
addThread.setBorder(null);
addThread.addActionListener(e -> {
results = new JPanel();
results.setBounds(0, y, 550, 150);
results.setBackground(Color.blue);
results.setLayout(null);
jFrame.add(results);
jFrame.repaint();
y = y+ 150;
});
// Remove
JButton removeThread = new JButton();
removeThread.setBorder(null);
removeThread.setBounds(340, 0, 25, 25);
removeThread.setText("-");
removeThread.addActionListener(e -> {
});
panelAddThread.add(threadLabel);
panelAddThread.add(removeThread);
panelAddThread.add(addThread);
jFrame.add(panelAddThread); }
}

I understand that you are asking for the code for the ActionListener for removeThread (JButton).
results is actually the last JPanel that you added, so that is the JPanel that you need to remove. However, once you remove it, you need to assign it to the new, last JPanel, i.e. the second last JPanel that was added.
Method getComponents returns all the components that were added, in the order that they were added. When you remove a component from a Container and subsequently call method getComponents, the array returned will not contain the component that you just removed. Hence the new, last JPanel is the last element in the array returned by method getComponents.
All that remains is to handle the "edge" cases.
Here is the code for the actionPerformed method:
removeThread.addActionListener(e -> {
if (results != null) {
jFrame.remove(results);
jFrame.repaint();
y -= 150;
Container contentPane = jFrame.getContentPane();
Component[] cmpts = contentPane.getComponents();
int count = cmpts.length;
if (count > 1) {
results = (JPanel) cmpts[count - 1];
}
else {
results = null;
}
}
});
If the user clicks removeThread before clicking addThread then results will be null.
If there is only one, added JPanel and we remove it, then we need to set results to null.
For completeness, here is the entire program, including the above changes.
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class lab3 {
static int y = 50;
static JButton addThread;
static JPanel results;
public static void main(String[] args) {
JFrame jFrame = new JFrame();
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setSize(550, 650);
jFrame.setTitle("Lab3");
jFrame.setVisible(true);
JPanel panelAddThread = new JPanel();
panelAddThread.setLayout(null);
panelAddThread.setBounds(0, 0, 550, 50);
panelAddThread.setBackground(Color.red);
JLabel threadLabel = new JLabel();
threadLabel.setText("Thread count: ");
addThread = new JButton();
addThread.setBounds(300, 0, 25, 25);
addThread.setText("+");
addThread.setBorder(null);
addThread.addActionListener(e -> {
results = new JPanel();
results.setBounds(0, y, 550, 150);
results.setBackground(Color.blue);
results.setLayout(null);
jFrame.add(results);
jFrame.repaint();
y = y + 150;
});
// Remove
JButton removeThread = new JButton();
removeThread.setBorder(null);
removeThread.setBounds(340, 0, 25, 25);
removeThread.setText("-");
removeThread.addActionListener(e -> {
if (results != null) {
jFrame.remove(results);
jFrame.repaint();
y -= 150;
Container contentPane = jFrame.getContentPane();
Component[] cmpts = contentPane.getComponents();
int count = cmpts.length;
if (count > 1) {
results = (JPanel) cmpts[count - 1];
}
else {
results = null;
}
}
});
panelAddThread.add(threadLabel);
panelAddThread.add(removeThread);
panelAddThread.add(addThread);
jFrame.add(panelAddThread);
}
}
However, I would write your program differently such that it uses Swing's layout managers. Consider the following:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class LabThree implements Runnable {
private JFrame frame;
private JPanel container;
private JPanel results;
public void run() {
buildAndDisplayGui();
}
private void buildAndDisplayGui() {
frame = new JFrame("Lab 3");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createButtonsPanel(), BorderLayout.PAGE_START);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createButtonsPanel() {
JPanel buttonsPanel = new JPanel(new FlowLayout(FlowLayout.TRAILING));
buttonsPanel.setBackground(Color.red);
JButton addThreadButton = new JButton("\u2795");
addThreadButton.addActionListener(this::addThread);
buttonsPanel.add(addThreadButton);
JButton removeThreadButton = new JButton("\u2796");
removeThreadButton.addActionListener(this::removeThread);
buttonsPanel.add(removeThreadButton);
return buttonsPanel;
}
private JScrollPane createMainPanel() {
container = new JPanel();
container.setLayout(new BoxLayout(container, BoxLayout.PAGE_AXIS));
JScrollPane scrollPane = new JScrollPane(container);
scrollPane.setPreferredSize(new Dimension(570, 620));
return scrollPane;
}
private void addThread(ActionEvent event) {
results = new JPanel();
results.setBackground(Color.blue);
Dimension dim = new Dimension(550, 150);
results.setMaximumSize(dim);
results.setMinimumSize(dim);
results.setPreferredSize(dim);
container.add(results);
container.revalidate();
}
private void removeThread(ActionEvent event) {
if (results != null) {
container.remove(results);
Component[] cmpts = container.getComponents();
int count = cmpts.length;
if (count > 0) {
results = (JPanel) cmpts[count - 1];
}
else {
results = null;
}
container.revalidate();
container.repaint();
}
}
public static void main(String[] args) {
EventQueue.invokeLater(new LabThree());
}
}
All components added to a JFrame are actually added to its content pane which, by default, is a JPanel whose [default] layout manager is BorderLayout.
Usually you should call method setVisible (of class JFrame) only after you have added all the components.
After the GUI is displayed and you add or remove components from a container (such as JPanel), you need to call method revalidate. Sometimes you also need to call method repaint after you have called method revalidate.
If you click addThreadButton many times, not all the added JPanels will be visible, hence I use JScrollPane.
The text for addThreadButton is the Unicode heavy plus symbol and the text for removeThreadButton is the heavy minus symbol.
The ActionListeners are implemented using method references.
Although not required, it is recommended to explicitly launch the event dispatch thread (EDT), which is done in method main in the above code.

Alignment of RadioButtons in Java GUI

Here is what my program is suppose to look like:
but I can't seem to get my radio buttons and my JLabel to be aligned properly. How do I align my radio buttons on the right and stacked? Also, how do I get my JLabel and JTextField to show stacked?
Here is my code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class SeriesCalc extends JFrame {
private final int WIDTH = 300;
private final int HEIGHT = 300;
private JFrame frame = new JFrame("Recursion");
private JPanel panel = new JPanel();
private JPanel labels = new JPanel();
private JPanel buttons = new JPanel();
private JPanel radioButtonsPanel = new JPanel();
private JLabel inputLabel = new JLabel("Enter i:");
private JLabel resultLabel = new JLabel("Result:");
private JTextField inputField = new JTextField(15);
private JTextField resultField = new JTextField(15);
private JButton compute = new JButton("Compute");
private JRadioButton iterative, recursive;
public SeriesCalc() {
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
radioButtonsPanel.add(iterative = new JRadioButton("Iterative"));
radioButtonsPanel.add(recursive = new JRadioButton("Recursive"));
add(radioButtonsPanel);
ButtonGroup radioButtons = new ButtonGroup();
radioButtons.add(iterative);
radioButtons.add(recursive);
iterative.addActionListener(new Calculations());
recursive.addActionListener(new Calculations());
compute.addActionListener(new Calculations());
resultField.setEditable(false);
panel.setLayout(new GridLayout(4, 1));
labels.add(inputLabel);
labels.add(inputField);
labels.add(resultLabel);
labels.add(resultField);
buttons.add(compute);
panel.add(radioButtonsPanel);
panel.add(labels);
panel.add(buttons);
frame.getContentPane().add(panel);
}
public void display() {
frame.setSize(WIDTH, HEIGHT);
frame.setVisible(true);
}
public class Calculations implements ActionListener {
public void actionPerformed(ActionEvent e) {
Object calc = e.getSource();
try {
if (calc == compute) {
if (iterative.isSelected()) {
double n = Double.parseDouble(inputField.getText());
double product = 1;
for (int i = 3; i < n; i++) {
product *= i;
}
resultField.setText(Double.toString(product));
} else if (recursive.isSelected()) {
double i = Double.parseDouble(inputField.getText());
double y = 0;
if (i == 1) {
resultField.setText(Double.toString(i / (2. * i + 1)));
} else {
resultField.setText(Double.toString(i / (2. * i + 1)+ (i -1)));
}
}
}
} catch (NumberFormatException nfe) {
System.err.println(nfe.getMessage());
}
}
}
public static void main(String[] args) {
SeriesCalc calculator = new SeriesCalc();
calculator.display();
}
}

I see some errors in your program:
You're extending JFrame and creating an instance of it in the same program. Use one or the other (I recommend the latter), See Using extends vs calling it inside of class.
You're setting frame.setSize() while this isn't an error it's always better to call frame.pack() in your program. It will respect the minimum size where all the components are shown in their preferredSizes. If you need an exact size for your window override getPreferredSize() method instead.
You're not placing your program on the Event Dispatch Thread (EDT), this could cause threading issues in the future as Swing is not thread safe, this can be solved with:
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
//Call your constructor here
}
});
}
but I can't seem to get my radio buttons and my JLabel to be aligned properly
This is because a JPanel's default layout manager is FlowLayout and thus it will place your components in a single row.
My idea to get to your desired GUI was to use a single GridLayout with 0 rows (it will add as many as needed) and 2 columns, and where you need a "blank" space you can add empty JLabels.
I didn't placed an ActionListener on my code as this question is about the GUI design not the logic inside it.
I think I'm not missing anything, this is the output that the below code creates:
import java.awt.GridLayout;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class SeriesCalc {
private JFrame frame;
private JRadioButton iterative;
private JRadioButton recursive;
private ButtonGroup group;
private JLabel label;
private JLabel resultLabel;
private JTextField field;
private JTextField resultField;
private JButton computeButton;
private JPanel pane;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new SeriesCalc().createAndShowGui();
}
});
}
public void createAndShowGui() {
frame = new JFrame(getClass().getSimpleName());
pane = new JPanel();
pane.setLayout(new GridLayout(0, 2, 2, 5));
iterative = new JRadioButton("Iterative");
recursive = new JRadioButton("Recursive");
group = new ButtonGroup();
group.add(iterative);
group.add(recursive);
computeButton = new JButton("Compute");
label = new JLabel("Enter \"i\": ");
resultLabel = new JLabel("Result: ");
field = new JTextField(5);
resultField = new JTextField(5);
resultField.setEnabled(false);
pane.add(new JLabel(""));
pane.add(iterative);
pane.add(new JLabel(""));
pane.add(recursive);
pane.add(label);
pane.add(field);
pane.add(new JLabel(""));
pane.add(computeButton);
pane.add(resultLabel);
pane.add(resultField);
frame.add(pane);
frame.pack();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

I don´t know if you are using an IDE like Eclipse or NetBeans. In Eclipse for example, you can open this class with windowbuilder and you could visualize how your Frame will appear. Obviously you can move element in this view (window builder) and put all objects where you want and the size you want. In the next image you could see the view of an edit of a Frame if you open it with window builder in mode design in Eclipse. In this mode (design) you can put absolute layout to these objects and they can be put where you want with that layout. I recommend you to use an IDE like eclipse for Java Developing, it is very useful and it has a lot of facilities. I hope I could help you:
enter image description here

Using button in a panel class to call ActionListener in the frame class

I started codig Java last weekend and I've read most of the basic stuff. I'm trying to separate my frame from main method, and panels from the frame so they are all in separate class files. I have trouble calling ActionLister in "Frame1" class with a button (buttonBack) in the "TheGame" class. The button should trigger the Listener which in turn should remove theGame panel and add mainMenu panel to frame1. I know that CardLayout is better suited for swapping panels but i want to learn the limits and workarounds before i go do it the "easy" way, i feel that you learn much more that way.
Here is some of my code:
Main:
public class Main {
public static void main(String[] args){
Frame1 frame1 = new Frame1();
frame1.frame1();
}
}
Frame1:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
class Frame1 {
private JFrame frame1 = new JFrame("Name");
public void frame1() {
TheGame theGame = new TheGame();
MainMenu mainMenu = new MainMenu();
// Frame options
frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame1.setLocationRelativeTo(null);
// Creating a top menu
JMenuBar menubar = new JMenuBar();
frame1.setJMenuBar(menubar);
JMenu file = new JMenu("File");
menubar.add(file);
JMenu help = new JMenu("Help");
menubar.add(help);
JMenuItem exit = new JMenuItem("Exit");
file.add(exit);
JMenuItem about = new JMenuItem("About");
help.add(about);
// Creating action for the menuitem "exit".
class exitaction implements ActionListener{
public void actionPerformed (ActionEvent e){
System.exit(0);
}
}
exit.addActionListener(new exitaction());
// Creating listener for the menuitem "about".
class aboutaction implements ActionListener{
public void actionPerformed (ActionEvent e){
JDialog dialogabout = new JDialog();
JOptionPane.showMessageDialog(dialogabout, "Made by: ");
}
}
about.addActionListener(new aboutaction());
// Add the panels, pack and setVisible
theGame.theGame();
mainMenu.mainMenu();
frame1.add(theGame.getGUI());
// This is the ActionListener i have trouble connecting with the buttonBack in the "theGame" class
class Action implements ActionListener{
public void actionPerformed (ActionEvent e){
frame1.remove(theGame.getGUI());
frame1.add(MainMenu.getGUI());
}
}
frame1.pack();
frame1.setVisible(true);
}
public JFrame getGUI() {
return frame1;
}
}
MainMenu:
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JLabel;
import javax.swing.JPanel;
class MainMenu {
private JPanel mainMenu = new JPanel (new GridBagLayout());
public void mainMenu() {
// Using the GridBagLayout therefore creating the constraints "grid"
GridBagConstraints grid = new GridBagConstraints();
// Adjusting grid insets
grid.insets = new Insets(10, 10, 10, 10);
// Creating Label
JLabel introduction = new JLabel("Name");
grid.gridx = 1;
grid.gridy = 3;
mainMenu.add(introduction, grid);
// Creating buttons Start Game, Highscore and Exit Game
JButton buttonNewGame = new JButton("New Game");
buttonNewGame.setPreferredSize(new Dimension(200, 50));
grid.gridx = 1;
grid.gridy = 5;
mainMenu.add(buttonNewGame, grid);
JButton buttonHighscore = new JButton("Highscore");
buttonHighscore.setPreferredSize(new Dimension(200, 50));
grid.gridx = 1;
grid.gridy = 6;
mainMenu.add(buttonHighscore, grid);
JButton buttonExit = new JButton("Exit Game");
buttonExit.setPreferredSize(new Dimension(200, 50));
grid.gridx = 1;
grid.gridy = 7;
mainMenu.add(buttonExit, grid);
}
public JComponent getGUI() {
return mainMenu;
}
}
TheGame:
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JLabel;
import javax.swing.JPanel;
class TheGame {
private JPanel theGame = new JPanel (new GridBagLayout());
public void theGame() {
// Using the GridBagLayout therefore creating the constraints "grid"
GridBagConstraints grid = new GridBagConstraints();
// Adjusting grid insets
grid.insets = new Insets(10, 10, 10, 10);
// Creating a label
JLabel label1 = new JLabel("Press the BACK button to go back to Main Menu");
label1.setVisible(true);
grid.gridx = 1;
grid.gridy = 0;
theGame.add(label1,grid);
// Creating BACK button
JButton buttonBack = new JButton("BACK");
buttonBack.setVisible(true);
grid.gridx = 1;
grid.gridy = 1;
buttonBack.addActionListener(new --); // This is the button i want to connect with the ActionListener on Frame1 class
theGame.add(buttonBack, grid);
}
public JComponent getGUI() {
return theGame;
}
}
I've tried moving the ActionListener outside of methods, inside the Main, declaring it static, but haven't been able to call it anyways. I've also looked at other posts like this: Add an actionListener to a JButton from another class but have not been able to implement it in to my code.
Any help is appreciated.

The best answer -- use MVC (model-view-controller) structure (and CardLayout) for the swapping of your views. If you don't want to do that, then your listener should have a reference to the container that does the swapping, and so that the listener can notify this container that a swap should occur. The container will then call its own code to do the swapping. To do this you need to pass references around including a reference to the main GUI to wherever it is needed. This can get messy, which is why MVC, which is more work, is usually better -- fewer connections/complexity in the long term.
Side note -- don't pass a JDialog into a JOptionPane as a JOptionPane is a specialized JDialog, and you shouldn't have a top level window displaying a top level window. Instead pass in a JPanel.
For example:
import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class PassRef {
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
createAndShowGui();
});
}
private static void createAndShowGui() {
MyMain mainPanel = new MyMain();
JFrame frame = new JFrame("Pass Reference");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
}
class MyMain extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = 450;
private CardLayout cardLayout = new CardLayout();
private MenuView menuView = new MenuView(this);
private ActionView1 actionView1 = new ActionView1(this);
public MyMain() {
setLayout(cardLayout);
add(menuView, MenuView.NAME);
add(actionView1, ActionView1.NAME);
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
} else {
return new Dimension(PREF_W, PREF_H);
}
}
public void showCard(String key) {
cardLayout.show(this, key);
// or swap by hand if you don't want to use CardLayout
// but remember to revalidate and repaint whenever doing it by hand
}
}
class MenuView extends JPanel {
public static final String NAME = "Menu View";
public MenuView(MyMain myMain) {
setName(NAME);
setBorder(BorderFactory.createTitledBorder("Menu"));
add(new JButton(new GoToAction("Action 1", ActionView1.NAME, myMain)));
}
}
class ActionView1 extends JPanel {
public static final String NAME = "Action View 1";
public ActionView1(MyMain myMain) {
setName(NAME);
setBorder(BorderFactory.createTitledBorder(NAME));
add(new JButton(new GoToAction("Main Menu", MenuView.NAME, myMain)));
}
}
class GoToAction extends AbstractAction {
private String key;
private MyMain myMain;
public GoToAction(String name, String key, MyMain myMain) {
super(name);
this.key = key;
this.myMain = myMain;
}
#Override
public void actionPerformed(ActionEvent e) {
myMain.showCard(key);
}
}

why is repaint() not working?

I am trying to add the buttons to the centerPanel that I created, then add that panel to the main center borderlayout. for some reason though my tab will not repaint anymore. It worked fine a while ago when I had the DrawFieldsListener class in the same class file as the MagicSquare, but nothing in the code has changed from my splitting them into two class files. So i really don't know what is going on. When it did repaint before, it would also take a long time. Any help? thanks!
All source for the project is on GitHub if it is easier to read and understand there: https://github.com/andrefecto/Academic-Convivium-Project
MagicSquare Class:
package magicSquare;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class MagicSquare extends JPanel {
JLabel sizeLabel = new JLabel("Enter A Square Size: ");
JButton setSize;
static JButton calculate;
static JButton reset;
static JTextField squareSize;
static JTextField field;
public static ArrayList<JTextField> inputFields = new ArrayList<JTextField>();
public static ArrayList<Integer> inputs = new ArrayList<Integer>();
public static ArrayList<Integer> totals = new ArrayList<Integer>();
public static int squared = 0;
public static int square = 0;
public static JPanel centerPanel = new JPanel();
public static JPanel bottomPanel = new JPanel();
public MagicSquare (){
setLayout(new BorderLayout());
JPanel subPanel = new JPanel();
subPanel.add(sizeLabel);
squareSize = new JTextField();
squareSize.setColumns(6);
subPanel.add(squareSize);
setSize = new JButton("Enter");
subPanel.add(setSize);
setSize.addActionListener(new DrawFieldsListener());
add(subPanel, BorderLayout.NORTH);
add(new DrawFieldsListener(), BorderLayout.CENTER);
}
}
my DrawFieldsListener class:
package magicSquare;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JTextField;
class DrawFieldsListener extends JPanel implements ActionListener {
int square = MagicSquare.square;
int squared = MagicSquare.squared;
JPanel centerPanel = MagicSquare.centerPanel;
JTextField squareSize = MagicSquare.squareSize;
JTextField field = MagicSquare.field;
ArrayList<JTextField> inputFields = MagicSquare.inputFields;
JButton calculate = MagicSquare.calculate;
JButton reset = MagicSquare.reset;
JPanel bottomPanel = MagicSquare.bottomPanel;
public void actionPerformed(ActionEvent e){
square = Integer.parseInt(squareSize.getText());
squared = square*square;
centerPanel.setLayout(new GridLayout(square, square));
for(int i = 0; i < squared; i++){
field = new JTextField();
field.setColumns(3);
inputFields.add(field);
centerPanel.add(inputFields.get(i));
System.out.println("DRAWING");
}
add(centerPanel, BorderLayout.CENTER);
System.out.println("ADDING ADDITINOAL BUTTONS");
additionalButtons();
System.out.println("ADDED ADDITINOAL BUTTONS");
System.out.println("REPAINTING");
repaint();
System.out.println("REPAINTED");
}
public void additionalButtons(){
calculate = new JButton("Calculate");
reset = new JButton("Reset");
bottomPanel.setLayout(new GridLayout(2, 2));
bottomPanel.add(reset);
bottomPanel.add(calculate);
add(bottomPanel, BorderLayout.SOUTH);
calculate.addActionListener(new CalculateListener());
reset.addActionListener(new ResetListener());
}
}

Mistake #1
public static JPanel centerPanel = new JPanel();
Followed by...
class DrawFieldsListener extends JPanel implements ActionListener {
//...
JPanel centerPanel = MagicSquare.centerPanel;
static is not a cross object communication mechanism...and now I have no idea who is suppose to be responsible for managing the centerPanel...
Remember, static is not your friend, beware of how it is used
Mistake #2
setSize.addActionListener(new DrawFieldsListener());
add(subPanel, BorderLayout.NORTH);
add(new DrawFieldsListener(), BorderLayout.CENTER);
You are creating two instances of DrawFieldsListener (which is a panel), one is acting as the ActionListener and one is acting as the view, but which one is actually housing MagicSquare.centerPanel as a component can only have one parent...
Mistake #3
Not revalidating the container after you have changed it...
public void actionPerformed(ActionEvent e) {
square = Integer.parseInt(squareSize.getText());
squared = square * square;
centerPanel.setLayout(new GridLayout(square, square));
for (int i = 0; i < squared; i++) {
field = new JTextField();
field.setColumns(3);
inputFields.add(field);
centerPanel.add(inputFields.get(i));
System.out.println("DRAWING");
}
add(centerPanel, BorderLayout.CENTER);
System.out.println("ADDING ADDITINOAL BUTTONS");
additionalButtons();
System.out.println("ADDED ADDITINOAL BUTTONS");
System.out.println("REPAINTING");
revalidate();
repaint();
System.out.println("REPAINTED");
}
Swing is lazy when it comes to container management, it assumes that you will want to do a number of adds or removes, so it won't update the container hierarchy layout until you ask it to, as the operation can be expensive
A better solution...
Isolate responsibility and provide information to your objects in a de-coupled manner.
For example, the DrawFieldsListener shouldn't care about MagicSquare, but should provide a means by which "some body" can tell it how many squares it should create.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MagicSquare extends JPanel {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new MagicSquare());
frame.setSize(400, 400);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
JLabel sizeLabel = new JLabel("Enter A Square Size: ");
JButton setSize;
private JSpinner squareSize;
JTextField field;
public MagicSquare() {
setLayout(new BorderLayout());
JPanel subPanel = new JPanel();
subPanel.add(sizeLabel);
squareSize = new JSpinner();
subPanel.add(squareSize);
setSize = new JButton("Enter");
subPanel.add(setSize);
DrawFieldsListener dfl = new DrawFieldsListener();
setSize.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
int gridSize = (int) squareSize.getValue();
dfl.makeGrid(gridSize);
}
});
add(subPanel, BorderLayout.NORTH);
add(dfl, BorderLayout.CENTER);
}
class DrawFieldsListener extends JPanel {
private JButton calculate;
private JButton reset;
private ArrayList<JTextField> inputFields = new ArrayList<JTextField>();
private ArrayList<Integer> inputs = new ArrayList<Integer>();
private ArrayList<Integer> totals = new ArrayList<Integer>();
private int squared = 0;
private int square = 0;
private JPanel centerPanel = new JPanel();
private JPanel bottomPanel = new JPanel();
public void makeGrid(int gridSize) {
square = gridSize;
squared = square * square;
centerPanel.setLayout(new GridLayout(square, square));
for (int i = 0; i < squared; i++) {
field = new JTextField();
field.setColumns(3);
inputFields.add(field);
centerPanel.add(inputFields.get(i));
System.out.println("DRAWING");
}
add(centerPanel, BorderLayout.CENTER);
System.out.println("ADDING ADDITINOAL BUTTONS");
additionalButtons();
System.out.println("ADDED ADDITINOAL BUTTONS");
System.out.println("REPAINTING");
revalidate();
repaint();
System.out.println("REPAINTED");
}
public void additionalButtons() {
calculate = new JButton("Calculate");
reset = new JButton("Reset");
bottomPanel.setLayout(new GridLayout(2, 2));
bottomPanel.add(reset);
bottomPanel.add(calculate);
add(bottomPanel, BorderLayout.SOUTH);
// calculate.addActionListener(new CalculateListener());
// reset.addActionListener(new ResetListener());
}
}
}

Close Gps on BoxLayout

I have created a setup of buttons using Box.
The problem is there are gaps between all the buttons.
Below is an MCVE version of my code. What I want to achieve is that the buttons "ONE" and "TWO" are touching side by side, with no gap, and buttons "ONE and "ONE" are touching top to bottom with no gap, and for this to continue throughout the setup.
I have read about glue and have tried to use it, but I have not been able to work it out. I am not able to use another layout other than Box as it will not fit in with the rest of my project.
public class Customers {
public static JFrame frame = new JFrame();
public static void frameGui(JPanel panel, String name){
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(panel);
frame.setSize(1200,500);
frame.setVisible(true);
}
public static void ScrollCustomersGui(){
Box box = Box.createVerticalBox();
box.add(customersTableHeadings(box));
box.add(customersTableHeadings(box));
box.add(customersTableHeadings(box));
box.add(customersTableHeadings(box));
JScrollPane scroll = new JScrollPane(box);
JPanel All = new JPanel(new BorderLayout());
All.add(scroll);
frameGui(All, "Customers");
}
public static JPanel customersTableHeadings(Box panel){
Font font = new Font("Courier", Font.BOLD,12);
JPanel customersTable = new JPanel();
JButton custid = new JButton("ONE");
JButton surname = new JButton("TWO");
customersTable.add(custid);
customersTable.add(surname);
return customersTable;
}
}

BoxLayout is designed to distribute unused space among components; struts, glue and filler won't change this. You can use the approach suggested here and here to alter the preferred size of the enclosing scroll pane. More generally, you can implement the scrollable interface. In addition, Swing GUI objects should be constructed and manipulated only on the event dispatch thread.
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
/** #se https://stackoverflow.com/a/26829171/230513 */
public class Customers {
private static final int N = 16;
private void display() {
Box box = Box.createVerticalBox();
for (int i = 0; i < N; i++) {
box.add(customersTableHeadings());
}
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new JScrollPane(box) {
int w = box.getPreferredSize().width;
int h = box.getPreferredSize().height;
#Override
public Dimension getPreferredSize() {
return new Dimension(9 * w / 8, h / 3);
}
});
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private JPanel customersTableHeadings() {
JPanel customersTable = new JPanel();
JButton custid = new JButton("ONE");
JButton surname = new JButton("TWO");
customersTable.add(custid);
customersTable.add(surname);
return customersTable;
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
new Customers().display();
});
}
}

I found the answer myself. By adding the horizontal and vertical inside the same loop, and by enclosing this in a JApplet it closes the gap.
Below is a full working version of the code:
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import javax.swing.Box;
import javax.swing.JApplet;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
public class Box1 extends JApplet {
public void init() {
Box bv = Box.createVerticalBox();
box(bv);
JScrollPane scroll = new JScrollPane(bv);
JPanel All = new JPanel(new BorderLayout());
All.add(scroll);
Container cp = getContentPane();
cp.add(All);
}
public static void main(String[] args) {
frameGui(new Box1(), "Customers");
}
public static void frameGui (JApplet applet, String name) {
JFrame frame = new JFrame();
frame.getContentPane().removeAll();
frame.setTitle(name);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(applet);
frame.setSize(1200, 500);
applet.init();
applet.start();
frame.setVisible(true);
}
public static Box box(Box boxvert){
for (int i = 0; i < 50; i++){
JTextField one = new JTextField("ONE");
one.setMaximumSize(new Dimension (150,20));
JTextField two = new JTextField("TWO");
two.setMaximumSize(new Dimension (150,20));
Box horizontalBox = Box.createHorizontalBox();
horizontalBox.add(one);
horizontalBox.add(two);
boxvert.add(horizontalBox);
}
return boxvert;
}
}