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Java swing graphics not updating

I have a java application that uses Swing graphics which has a 2D array of textfields, each of which are updating their text properly throughout the application. On each iteration of change, I change the text of the textfield then I make it's background green for half a second and turn it back to white. The issue is that, after the first iteration of the change, the textfields no longer flash green. When I comment out the portion that converts the background back to white, the rest works and the cells progressively turn green one by one (correctly), which indicates that it is working and executing properly. I tried to address this by repainting and revalidating the UI but it's not working. What is going on?
Below is my code that updates the UI.
try {
textfieldArray[row][col].repaint();
textfieldArray[row][col].revalidate();
textfieldArray[row][col].setBackground(Color.green);
textfieldArray[row][col].repaint();
textfieldArray[row][col].revalidate();
Thread.sleep(300);
textfieldArray[row][col].setBackground(Color.white);
textfieldArray[row][col].repaint();
textfieldArray[row][col].revalidate();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

Swing is a single threaded framework, it also NOT thread safe. This means two things.
First, you should never perform any long running or blocking operations within the context of the Event Dispatching Thread and...
Secondly, you should never update/modify the UI, or anything the UI depends on, from outside the context of the Event Dispatching Thread.
This means, your Thread.sleep is blocking the EDT, preventing from process paint requests.
Instead, you need some way you can trigger an update to occur after a specified delay. If that doesn't scream Swing Timer, I don't know what does
I would highly recommend taking the time to read through Concurrency in Swing for the background of why your code isn't working and possibly How to Use Swing Timers for a solution
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
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.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
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 TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JTextField field;
public TestPane() {
setLayout(new GridBagLayout());
field = new JTextField("All your bases beloging to us", 20);
JButton blink = new JButton("Blink");
Timer timer = new Timer(500, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
field.setForeground(null);
field.setBackground(null);
}
});
timer.setRepeats(false);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(field, gbc);
blink.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
field.setForeground(Color.WHITE);
field.setBackground(Color.GREEN);
timer.start();
}
});
add(blink, gbc);
}
}
}

Why does JPopupMenu take 2 passes of UIThread before rendering?

The first pass appears to either invalidate the drawable area or draws the background. And the second pass renders the menu. If there is any delay (as the example below exaserbates) then you get a grey square flickering effect.
This is JDK8 on Linux.
How can I stop this flicker effect?
public class MenuTester {
public static void main(String[] args) {
final JFrame frame = new JFrame();
frame.setBounds(100, 100, 300, 200);
final JButton button = new JButton("Show Menu");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
final JPopupMenu popupMenu = new JPopupMenu();
popupMenu.add(new JMenuItem("aaaa"));
popupMenu.add(new JMenuItem("bbbb"));
popupMenu.add(new JMenuItem("cccc"));
popupMenu.setLocation(100, 100);
popupMenu.setVisible(true);
try {
Thread.sleep(2000); // Leave enough time to clearly see the ?invalidated/background? area.
} catch (InterruptedException ex) {
// Nothing to do
}
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
// Hide after 1 second
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
// Nothing to do
}
popupMenu.setVisible(false);
}
});
}
});
frame.add(button);
frame.setVisible(true);
}
}

Swing has, for as long as I remember it, had a "delay" when showing windows, this might have do with the time between the frame been realised by the OS and connection of the native message and event queues, but this is pure observation
I took you code and by simply by wrapping the frame's creation into a EventQueue.invokeLater was able to get a similar behaviour
You will get different results on different systems depending on there system up and configurations
What is the event that causes the window to be rendered in the first pass?
All I did was took your code and wrapped the creation the UI in an EventQueue.invokeLater, for example...
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MenuTester {
public static void main(String[] args) {
new MenuTester();
}
public MenuTester() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
final JFrame frame = new JFrame();
frame.setBounds(100, 100, 300, 200);
final JButton button = new JButton("Show Menu");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
final JPopupMenu popupMenu = new JPopupMenu();
popupMenu.add(new JMenuItem("aaaa"));
popupMenu.add(new JMenuItem("bbbb"));
popupMenu.add(new JMenuItem("cccc"));
popupMenu.setLocation(100, 100);
popupMenu.setVisible(true);
// try {
// Thread.sleep(2000); // Leave enough time to clearly see the ?invalidated/background? area.
// } catch (InterruptedException ex) {
// // Nothing to do
// }
// SwingUtilities.invokeLater(new Runnable() {
// #Override
// public void run() {
// // Hide after 1 second
// try {
// Thread.sleep(1000);
// } catch (InterruptedException ex) {
// // Nothing to do
// }
// popupMenu.setVisible(false);
// }
// });
}
});
frame.add(button);
frame.setVisible(true);
}
});
}
}
And is there a way to render the window as transparent during that first pass and opaque during the 2nd?
This is not a new problem, this has been the state of affair since I started with Swing at Java 1.3. What you're asking would mean you knew when the paint pass was done AND was complete. Swing isn't altogether stupid, it can make some clever decisions in order to optimise the rendering process (like not painting components which are visible)
The other problem is, with a JPopupMenu, you don't actually know if it's been displayed in a window or not (or just been displayed as a component on the glass pane for example) so the whole thing is woefully complicated

Adding Menu before beginning of game

For some reason my jFrame no longer pops up after I add the menu. Is there something I am missing? I'm trying to make a menu that pops up before the beginning of the game and has buttons "play" as well as a text box that allows the user to input a username.
Any suggestions for how I could fix my code? Thank you!
this is my Menu class:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JButton;
import javax.swing.JPanel;
public class Menu extends JPanel{
private static final long serialVersionUID = 1L;
public Menu() {
JPanel buttonPanel = new JPanel(new GridLayout());
JButton play = new JButton();
JButton help = new JButton();
buttonPanel.add(play);
buttonPanel.add(help);
setFocusable(true);
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
Game.started = true;
}
});
}
public void paint (Graphics g) {
super.paint(g);
g.setColor(Color.black);
g.fillRect(400, 400, Game.WIDTH, Game.HEIGHT);
}
}
and this is my Main class from which I run my program:
import java.awt.BorderLayout;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Main implements Runnable{
public void run() {
final JFrame frame = new JFrame();
frame.setTitle("Flying Square");
frame.setSize(Game.WIDTH, Game.HEIGHT);
//The menu
final Menu menu = new Menu();
final Game game = new Game();
frame.add(menu, BorderLayout.CENTER);
menu.setVisible(true);
try {while (Game.started == false) {
Thread.sleep(10);
}} catch (InterruptedException e){
e.printStackTrace();
}
frame.remove(menu);
//Main playing area
frame.add(game, BorderLayout.CENTER);
game.setVisible(true);
frame.revalidate();
// Put the frame on the screen
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
// add listeners
frame.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
flyingObject.jump();
}
});
frame.addKeyListener(new KeyListener() {
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_SPACE)
{
flyingObject.jump();
}
}
});
// Start game
Game.reset();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Main());
}
}

So, this...
try {while (Game.started == false) {
Thread.sleep(10);
}} catch (InterruptedException e){
e.printStackTrace();
}
Is blocking the Event Dispatching Thread, preventing it from processing any events and basically causing your program to hang.
This is not how you want to process responses from the user. Your Menu should be monitoring for input from the user, probably through one or more ActionListeners, when an action is triggered, it should be notifying some kind of controller, the controller can then make decisions about what it needs to do, like switch the panels for example
You're going to want to break your code down into at least three chunks, the "game" the "menu" and the "controller", this way it will be easier to manage, rather than trying to retrofit the functionality into an existing code
It would recommend having a look at
How to Use CardLayout to help you facilite the switching of the view
How to Use Key Bindings instead of KeyListener
Model-View-Controller
Observer Pattern

Loop Instead of Button for displaying images in JLabel? [duplicate]

in a java aplication I have a Jlabel which i want to assign a new image to every time i click a button, using a for loop i can get it to just display the last image skipping all in between images, i know there is a error in my logic here maybe i should not be using a for loop?? any advice
private String imageList[];
ImageIcon image;
imageList = new String[] {"src\\Tour_Eiffel_Wikimedia_Commons.jpg","src\\Ben.jpg", "src\\Rio.jpg", "src\\Liberty.jpg", "src\\Pyramid.jpg"};
//constructor setting first image to display on load
public GeographyGameGUI() {
image = new ImageIcon(imageList[0]);
imageLbl.setIcon(image);
}
//button method
private void nextBtnActionPerformed(java.awt.event.ActionEvent evt) {
for (imgCount = 1; imgCount < imageList.length; imgCount++) {
image = new ImageIcon(imageList[imgCount]);
imageLbl.setIcon(image);
}
if i dont use a for loop and simply use a counter (displayed below) which i declare outside of the button method it loops correctly displaying the images but runs into a ArrayIndexOutOfBoundsException. what is the best practice here? thanks
image = new ImageIcon(imageList[imgCount]);
imageLbl.setIcon(image);
imgCount++;

You're, essentially, blocking the Event Dispatching Thread, prevent it from updating the UI. See Concurrency in Swing for more details
Instead, you should use a javax.swing.Timer to loop over the images, allowing the UI to update before changing to the next one...
See How to use Swing Timers for more details.
Java arrays are zero indexed, this means that the first element in the array is a position 0, not 1
Don't reference src directly within your code, the src directory will not exist once the application is built and packaged
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
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 TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel label;
private String[] imageList = new String[] {"/Tour_Eiffel_Wikimedia_Commons.jpg","/Ben.jpg", "/Rio.jpg", "/Liberty.jpg", "/Pyramid.jpg"};
public TestPane() {
setLayout(new BorderLayout());
label = new JLabel();
add(label);
JButton btn = new JButton("Play");
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
btn.setEnabled(false);
Timer timer = new Timer(1000, new ActionListener() {
private int count;
#Override
public void actionPerformed(ActionEvent e) {
if (count < imageList.length) {
try {
label.setIcon(
new ImageIcon(
ImageIO.read(
TestPane.this.getClass().getResource(imageList[count]))));
} catch (IOException exp) {
exp.printStackTrace();
}
count++;
} else {
((Timer)e.getSource()).stop();
}
}
});
timer.stop();
}
});
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}

Your counter reaches the end of the array so you get out of bounds exception. After each increment you should check whether the end of array has been reached, and if so, set the counter to 0.
If you want to iterate over a few images with a delay on single click you need to use SwingWorker. Using delays in your action listener will suspend event dispatch thread, which means that no other updates or interactions with swing components will be available (it is likely that refreshes will not be done correctly too).
If you do a few updates (setIcon) in a very short time, Swing usually refreshes the component after the last of them, which means that only last image will be visible.
Have a look here: http://docs.oracle.com/javase/tutorial/uiswing/concurrency/worker.html

Hide a JFrame and display it again through a click on the dock icon

My application has a JFrame and checks every x seconds if something changed. So I would like to hide my JFrame via setVisible(false) on a click on the close button and redisplay it when the icon in the dock (I'm using Mac OS, but it should work the same way with the Windows task bar) is clicked. You know: many applications do this temporary hiding.
Have you got any ideas how to do this? How to listen on these click events?

Here is a little sample, how to hide/open window in the tray.
import java.awt.Image;
import java.awt.SystemTray;
import java.awt.Toolkit;
import java.awt.TrayIcon;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
public class Test {
public static void main(String[] args) throws Exception {
final JFrame frm = new JFrame("Test");
Image im = Toolkit.getDefaultToolkit().getImage("c:\\icons\\icon1.png");
final TrayIcon tri = new TrayIcon(im);
tri.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
frm.setVisible(true);
try {
SystemTray.getSystemTray().remove(tri);
} catch (Exception ex) {
ex.printStackTrace();
}
}
});
frm.addWindowListener(new WindowAdapter() {
#Override
public void windowClosing(WindowEvent e) {
try {
SystemTray.getSystemTray().add(tri);
} catch (Exception ex) {
ex.printStackTrace();
}
frm.setVisible(false);
}
});
frm.setSize(100, 100);
frm.setVisible(true);
}
}

Use the com.apple.eawt or java.awt.Desktop packages to listen to Events that occur when the application is closed, hidden or reactivated.
Particularly com.apple.eawt.AppReOpenedEvent is cast when the Dock Icon is clicked. When you handle the event with com.apple.eawt.AppReOpenedListener, set the frame visible again:
#Override
public void appReOpened(AppReOpenedEvent arg0) {
invalidate(); // Suppose these are optional, but make sure the layout is up to date
pack();
validate();
setVisible(true);
}