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dispose method only works once then fails to function

I'm having trouble with the functionality of dispose for my checkerboard (called Checkers) . For each checkerboard that I have, i want to be able to remove it by using dispose before calling another instance of my interface. Here is my progress so far:
Checkers class:
import java.awt.*;
import javax.swing.*;
import java.awt.Color.*;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
import java.util.Random;
public class Checkers extends JFrame
{
Random random = new Random();
private final int ROWS = 2;
private final int COLS = 5;
private final int GAP = 2;
private final int NUM = ROWS * COLS;
private int i;
public int score;
private JPanel pane = new JPanel(new GridLayout(ROWS,COLS, GAP,GAP));
private JPanel pane2 = new JPanel();
private JPanel pane3 = new JPanel();
private JButton btn1 = new JButton("Play A Game");
private JButton btn2 = new JButton("Exit");
private JButton btn3 = new JButton("Easy");
private JButton btn4 = new JButton("Intermediate");
private JButton btn5 = new JButton("Difficult");
private JLabel lbl1 = new JLabel ("score: " + score);
private JLabel gameLost = new JLabel("You lose! You got: " + score + " points");
private MyPanel [] panel = new MyPanel[NUM];
private Color col1 = Color.RED;
private Color col2 = Color.WHITE;
private Color col3 = Color.GREEN;
private Color tempColor;
public Checkers()
{
super("Checkers");
setSize(600,600);
setVisible(true);
setBackground(Color.BLACK);
setBoard();
}
public void setBoard()
// roates colors on the checkbaord
{
for (int i = 0; i < panel.length; i++) {
panel[i] = new MyPanel(this);
pane.add(panel[i]);
if (i % COLS == 0) {
tempColor = col1;
col1 = col2;
col2 = tempColor;}
if (i % 2 == 0) {
panel[i].setBackground(col1);}
else {
panel[i].setBackground(col2);}
}
//pane background colour and the size of this pane.
pane.setBackground(Color.BLACK);
pane.setPreferredSize(new Dimension(300,300));
//pane background colour and size of this pane.
pane2.setBackground(Color.white);
pane2.setPreferredSize(new Dimension(300,300));
//directions on the board where these panes appear.
add(pane, BorderLayout.WEST);
add(pane2, BorderLayout.EAST);
pane2.add(lbl1);
pane2.setLayout(new BoxLayout(pane2, BoxLayout.PAGE_AXIS));
}
public void incrementScore(){
score++;
lbl1.setText("Score: " + Integer.toString(score));
}
//This is the method for resetting via dispose - only works once.
public void restartBoard(){
this.dispose();
new Checkers();
}
}
And also the MyPanel class
public class MyPanel extends JPanel implements MouseListener {
private final Checkers checkers;
public MyPanel(Checkers checkers) {
this.checkers = checkers;
addMouseListener(this);
}
#Override
public void mouseClicked(MouseEvent e) {
setBackground(Color.BLACK);
checkers.incrementScore();
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
}
EXPECTED RESULT - What i'd like to do is be able to close the current version of interface by using the dispose method, and then opening a new instance of said interface.
ACTUAL RESULT - When opening an interface, then calling dispose method, it will work once. once you try to remove the 2nd interface when creating a 3rd interface, dispose will not function, and I cant see why this is.
Any help is welcome.

For what it's worth, this is an MCVE that shows your likely problem:
import java.awt.Dimension;
import javax.swing.*;
public class CheckersTest {
private static void createAndShowGui() {
Checkers checkers = new Checkers();
JButton restartButton = new JButton("Restart");
restartButton.addActionListener(event -> checkers.restartBoard());
JPanel restartPanel = new JPanel();
restartPanel.setPreferredSize(new Dimension(400, 400));
restartPanel.add(restartButton);
JFrame frame = new JFrame("Checkers Test");
frame.add(restartPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
class Checkers extends JFrame {
public Checkers() {
setPreferredSize(new Dimension(200, 200));
pack();
setLocationByPlatform(true);
setVisible(true);
}
public void restartBoard(){
this.dispose();
new Checkers();
}
}
The restart button refers to the original Checkers instance and so will not close any new instances created. The solution would be to get the restart method out of Checkers, create a Checkers field, and make sure the restart method refers to the visible Checkers instance:
import java.awt.Dimension;
import javax.swing.*;
public class CheckersTest {
private static Checkers checkers = new Checkers(); // holds reference
private static void restartBoard() {
if (checkers != null) {
checkers.dispose();
checkers = new Checkers(); // assign to reference field
}
}
private static void createAndShowGui() {
// !! Checkers checkers = new Checkers();
JButton restartButton = new JButton("Restart");
// !! restartButton.addActionListener(event -> checkers.restartBoard());
restartButton.addActionListener(event -> restartBoard());
JPanel restartPanel = new JPanel();
restartPanel.setPreferredSize(new Dimension(400, 400));
restartPanel.add(restartButton);
JFrame frame = new JFrame("Checkers Test");
frame.add(restartPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
class Checkers extends JFrame {
public Checkers() {
setPreferredSize(new Dimension(200, 200));
pack();
setLocationByPlatform(true);
setVisible(true);
}
}
Notes:
Again a much better design is not to swap JFrames but rather JPanel views
Note that the MCVE has code that reproduces the problem but avoids code not related to the problem. So it shows the restartBoard method, it compiles, but avoids game code since this is not relevant to the problem.

Responsive JFrame without Layout Manager

I am trying to do have two button in JFrame, and I call the setBounds method of them for setting the positions and size of them and also I passed null to setLayout1 because I want to usesetBounds` method of component.
Now I want to do something with my code that whenever I resize the frame buttons decoration will change in a suitable form like below pictures:
I know it is possible to use create an object from JPanel class and add buttons to it and at the end add created panel object to frame, but I am not allowed to it right now because of some reason (specified by professor).
Is there any way or do you have any suggestion?
My code is like this:
public class Responsive
{
public static void main(String[] args)
{
JFrame jFrame = new JFrame("Responsive JFrame");
jFrame.setLayout(null);
jFrame.setBounds(0,0,400,300);
JButton jButton1 = new JButton("button 1");
JButton jButton2 = new JButton("button 2");
jButton1.setBounds(50,50,100,100);
jButton2.setBounds(150,50,100,100);
jFrame.add(jButton1);
jFrame.add(jButton2);
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setVisible(true);
}
}

A FlowLayout with no horizontal spacing, some vertical spacing and large borders could achieve that easily. A null layout manager is never the answer to a 'responsive' robust GUI.
import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class ResponsiveGUI {
private JComponent ui = null;
ResponsiveGUI() {
initUI();
}
public void initUI() {
if (ui!=null) return;
ui = new JPanel(new FlowLayout(FlowLayout.CENTER, 0, 8));
ui.setBorder(new EmptyBorder(10,40,10,40));
for (int i=1; i<3; i++) {
ui.add(getBigButton(i));
}
}
public JComponent getUI() {
return ui;
}
private final JButton getBigButton(int number) {
JButton b = new JButton("Button " + number);
int pad = 20;
b.setMargin(new Insets(pad, pad, pad, pad));
return b;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception useDefault) {
}
ResponsiveGUI o = new ResponsiveGUI();
JFrame f = new JFrame("Responsive GUI");
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setLocationByPlatform(true);
f.setContentPane(o.getUI());
f.pack();
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}

You could try to use:
jFrame.addComponentListener(new ComponentListener() {
// this method invokes each time you resize the frame
public void componentResized(ComponentEvent e) {
// your calculations on buttons
}
});

Swing Component not displaying on the frame

I don't understand why the RackBuilder object I added to the frame does not get displayed.
The code runs and the frame gets generated. I expect to see a panel with 42 rows, each row containing a JLabel "test". Is there something incorrect/missing from my constructor?
public class RackBuilderTool extends JPanel{
public RackBuilderTool() {
super(new GridLayout(42, 0));
for (int i = 0; i < 42; i++) {
add(new JLabel("test"));
}
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("Rack Builder Tool");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RackBuilderTool rackBuilder = new RackBuilderTool();
rackBuilder.setOpaque(true);
frame.setContentPane(rackBuilder);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
Thanks!

import javax.swing.*;
import java.awt.*;
public class RackBuilderTool extends JPanel{
public RackBuilderTool() {
super(new GridLayout(42, 0));
for (int i = 0; i < 42; i++) {
add(new JLabel("test"));
}
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("Rack Builder Tool");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RackBuilderTool rackBuilder = new RackBuilderTool();
rackBuilder.setOpaque(true);
frame.setContentPane(rackBuilder);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
now it will show you 42 rows of your label.

Realized that the "run" button on Netbeans IDE is to run the entire project. As a result it was running another java file under the same project.
Once I right clicked on the java file I wanted to compile and clicked run it worked.
Thanks everyone for the help.

Java: Why doesn't my image show up?

I have created 2 classes that are working together to show pictures by clicking different buttons. In my EventEvent class I tried to make it so that when you press the "Picture 1" button, the variable ImageIcon xpic gets the value of ImageIcon vpic (which holds an image), after xpic has the same value as vpic my frame is supposed to somehow refresh so that xpic's new value applies and gets then shows the picture.
Why doesn't my image show up even though the button press repaints the JPanel the image is in?
Main class:
import java.awt.*;
import javax.swing.*;
public class EventMain extends JFrame{
EventEvent obje = new EventEvent(this);
// Build Buttons
JButton picB1;
JButton picB2;
JButton picB3;
JButton picB4;
JButton picB5;
//Build Panels
JPanel row0;
//Build Pictures
ImageIcon xpic;
ImageIcon vpic;
public EventMain(){
super("Buttons");
setLookAndFeel();
setSize(470, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GridLayout layout1 = new GridLayout(3,4);
setLayout(layout1);
picB1 = new JButton("Picture 1");
picB2 = new JButton("Picture 2");
picB3 = new JButton("Picture 3");
picB4 = new JButton("Picture 4");
picB5 = new JButton("Picture 5");
vpic = new ImageIcon(getClass().getResource("Images/vanessa.png"));
// Set up Row 0
row0 = new JPanel();
JLabel statement = new JLabel("Choose a picture: ", JLabel.LEFT);
JLabel picture = new JLabel(xpic);
// Set up Row 1
JPanel row1 = new JPanel();
// Set up Row 2
JPanel row2 = new JPanel();
//Listeners
picB1.addActionListener(obje);
FlowLayout grid0 = new FlowLayout (FlowLayout.CENTER);
row0.setLayout(grid0);
row0.add(statement);
row0.add(picture);
add(row0);
FlowLayout grid1 = new FlowLayout(FlowLayout.CENTER);
row1.setLayout(grid1);
row1.add(picB1);
row1.add(picB2);
add(row1);
FlowLayout grid2 = new FlowLayout(FlowLayout.CENTER);
row2.setLayout(grid2);
row2.add(picB3);
row2.add(picB4);
row2.add(picB5);
add(row2);
setVisible(true);
}
private void setLookAndFeel() {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.NimbusLookAndFeel");
} catch (Exception exc) {
}
}
public static void main(String[] args) {
EventMain con = new EventMain();
}
}
Class containing events:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class EventEvent implements ActionListener {
EventMain gui;
public EventEvent(EventMain in){
gui = in;
}
public void actionPerformed(ActionEvent event) {
String command = event.getActionCommand();
if (command.equals("Picture 1")){
gui.xpic = gui.vpic;
gui.row0.repaint();
}
}
}

You're confusing variables with objects. Just because you change the object associated with the xpic variable, don't assume that this will change the object (the Icon) held by the JLabel. There is no magic in Java, and changing the object that a variable refers to will have no effect on the prior object.
In other words, this:
gui.xpic = gui.vpic;
gui.row0.repaint();
will have no effect on the icon that the picture JLabel is displaying
To swap icons, you must call setIcon(...) on the JLabel. Period. You will need to make the picture JLabel a field, not a local variable, and give your GUI class a public method that allows outside classes to change the state of the JLabel's icon.
Also, you should not manipulate object fields directly. Instead give your gui public methods that your event object can call.
Edit
For example:
import java.awt.event.ActionEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class MyGui extends JPanel {
public static final String IMAGE_PATH = "https://duke.kenai.com/cards/.Midsize/CardFaces.png.png";
private static final int ROWS = 4;
private static final int COLS = 13;
private BufferedImage largeImg;
private List<ImageIcon> iconList = new ArrayList<>();
private JLabel pictureLabel = new JLabel();
private JButton swapPictureBtn = new JButton(new SwapPictureAction(this, "Swap Picture"));
private int iconIndex = 0;
public MyGui() throws IOException {
add(pictureLabel);
add(swapPictureBtn);
URL imgUrl = new URL(IMAGE_PATH);
largeImg = ImageIO.read(imgUrl);
for (int i = 0; i < ROWS; i++) {
for (int j = 0; j < COLS; j++) {
int x = (j * largeImg.getWidth()) / COLS;
int y = (i * largeImg.getHeight()) / ROWS;
int w = largeImg.getWidth() / COLS;
int h = largeImg.getHeight() / ROWS;
iconList.add(new ImageIcon(largeImg.getSubimage(x, y, w, h)));
}
}
pictureLabel.setIcon(iconList.get(iconIndex));
}
public void swapPicture() {
iconIndex++;
iconIndex %= iconList.size();
pictureLabel.setIcon(iconList.get(iconIndex));
}
private static void createAndShowGui() {
MyGui mainPanel;
try {
mainPanel = new MyGui();
JFrame frame = new JFrame("MyGui");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
#SuppressWarnings("serial")
class SwapPictureAction extends AbstractAction {
private MyGui myGui;
public SwapPictureAction(MyGui myGui, String name) {
super(name);
this.myGui = myGui;
}
#Override
public void actionPerformed(ActionEvent e) {
myGui.swapPicture();
}
}

See the createAction() method below and how it creates an AbstractAction. See also the tutorial related to using actions with buttons. http://docs.oracle.com/javase/tutorial/uiswing/misc/action.html
import javax.swing.*;
import javax.swing.plaf.nimbus.NimbusLookAndFeel;
import java.awt.*;
import java.awt.event.ActionEvent;
public class EventMain {
private static final ImageIcon PICTURE_1 = new ImageIcon(EventMain.class.getResource("images/v1.png"));
private static final ImageIcon PICTURE_2 = new ImageIcon(EventMain.class.getResource("images/v2.png"));
private JFrame frame;
EventMain create() {
setLookAndFeel();
frame = createFrame();
frame.getContentPane().add(createContent());
return this;
}
void show() {
frame.setSize(470, 300);
frame.setVisible(true);
}
private JFrame createFrame() {
JFrame frame = new JFrame("Buttons");
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
return frame;
}
private Component createContent() {
final JLabel picture = new JLabel();
JButton picB1 = new JButton(createAction("Picture 1", picture, PICTURE_1));
JButton picB2 = new JButton(createAction("Picture 2", picture, PICTURE_2));
JButton picB3 = new JButton(createAction("Picture 3", picture, PICTURE_1));
JButton picB4 = new JButton(createAction("Picture 4", picture, PICTURE_2));
JButton picB5 = new JButton(createAction("Picture 5", picture, PICTURE_1));
JLabel statement = new JLabel("Choose a picture: ", JLabel.LEFT);
// Create rows 1, 2, 3
JPanel panel = new JPanel(new GridLayout(3, 4));
panel.add(createRow(statement, picture));
panel.add(createRow(picB1, picB2));
panel.add(createRow(picB3, picB4, picB5));
return panel;
}
/**
* Create an action for the button. http://docs.oracle.com/javase/tutorial/uiswing/misc/action.html
*/
private Action createAction(String label, final JLabel picture, final Icon icon) {
AbstractAction action = new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
picture.setIcon(icon);
}
};
action.putValue(Action.NAME, label);
return action;
}
private Component createRow(Component... componentsToAdd) {
JPanel row = new JPanel(new FlowLayout(FlowLayout.CENTER));
for (Component component : componentsToAdd) {
row.add(component);
}
return row;
}
private void setLookAndFeel() {
try {
UIManager.setLookAndFeel(new NimbusLookAndFeel());
} catch (UnsupportedLookAndFeelException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new EventMain().create().show();
}
});
}
}

JPanel repaint issue

I have a JFrame which contains 2 JPanel subclass and 2 JLabel in BorderLayout. One of the JPanel contains JButtons and the other is used for displaying graphics. The JLabels are in north and south, the button JPanel in the west and the display JPanel in center.
The display JPanel requires constant refresh, so i invoke its repaint() method via the action event generated by swing timer. I also override its paintComponent() method to do my drawings.
Instead of displaying what i have drawn, the "content of the JFrame" is being drawn onto the display JPanel. I am aware that i can simply "clear" the display JPanel by using g.fillRect() or super.paintComponent() before doing my drawings.
I am just curious why this happens.
i'm using jdk 1.6u27. below is my code:
package test;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class Main {
public static void main(String[] args) {
Simulation sim = new Simulation();
}
}
class Simulation extends JFrame {
public JLabel state;
private JLabel id;
private ButtonPanel control;
private Display display;
public Simulation() {
id = new JLabel("Test");
state = new JLabel("Test");
control = new ButtonPanel();
display = new Display(this);
this.setLayout(new BorderLayout());
this.add(id, BorderLayout.NORTH);
this.add(control, BorderLayout.WEST);
this.add(display, BorderLayout.CENTER);
this.add(state, BorderLayout.SOUTH);
this.setSize(500, 600);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public ButtonPanel getControl() {
return this.control;
}
}
class ButtonPanel extends JPanel implements ActionListener {
public JButton b[] = new JButton[8];
public boolean bp[] = new boolean[8];
public ButtonPanel() {
this.setLayout(new GridLayout(8, 1));
for (int i = 0; i < b.length; i++) {
b[i] = new JButton(""+i);
b[i].addActionListener(this);
bp[i] = false;
this.add(b[i]);
}
}
public void actionPerformed(ActionEvent e) {
//do something
}
}
class Display extends JPanel implements ActionListener {
private Timer tm;
private int yco;
private Simulation sim;
public Display(Simulation sim) {
tm = new Timer(100, this);
tm.start();
yco = 0;
this.sim = sim;
}
#Override
public void paintComponent(Graphics g) {
//draw something
g.drawLine(0, yco, 100, 100);
}
public void actionPerformed(ActionEvent e) {
yco ++;
this.repaint();
}
}

Without super.paintComponent(g), the result depends on your platform's default for the opacity property of the JPanel UI delegate, PanelUI. Mine happens to be true, but you can experiment on your platform, as suggested below.
Addendum: "If you do not honor the opaque property you will likely see visual artifacts."—paintComponent(). The artifact you observe will vary by platform, but it is not atypical. In effect, you are breaking the promise to draw every pixel, and you see whatever is left over in some buffer.
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
public class Main {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
Simulation sim = new Simulation();
}
});
}
}
class Simulation extends JFrame {
public JCheckBox state;
private JLabel id;
private ButtonPanel control;
private Display display;
public Simulation() {
id = new JLabel("Test");
state = new JCheckBox("Opaque");
control = new ButtonPanel();
display = new Display(this);
this.setLayout(new BorderLayout());
this.add(id, BorderLayout.NORTH);
this.add(control, BorderLayout.WEST);
this.add(display, BorderLayout.CENTER);
this.add(state, BorderLayout.SOUTH);
state.addItemListener(new ItemListener() {
#Override
public void itemStateChanged(ItemEvent e) {
display.setOpaque(e.getStateChange() == ItemEvent.SELECTED);
}
});
state.setSelected(true);
this.pack();
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public ButtonPanel getControl() {
return this.control;
}
}
class ButtonPanel extends JPanel {
private static final int N = 8;
private List<JToggleButton> list = new ArrayList<JToggleButton>(N);
public ButtonPanel() {
this.setLayout(new GridLayout(0, 1));
for (int i = 0; i < N; i++) {
final JToggleButton b = new JToggleButton(String.valueOf(i));
b.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
//System.out.println(b.isSelected());
}
});
list.add(b);
this.add(b);
}
}
}
class Display extends JPanel {
private Simulation sim;
private Timer tm;
private int yco;
public Display(Simulation sim) {
this.setPreferredSize(new Dimension(320, 320));
this.setOpaque(true);
this.sim = sim;
tm = new Timer(100, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
yco++;
repaint();
}
});
tm.start();
}
#Override
public void paintComponent(Graphics g) {
//super.paintComponent(g);
g.drawLine(0, yco, getWidth() / 2, getHeight() / 2);
}
}