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make jbutton to turn on and off

My goal is creating a function that waits half second, set the jbutton's background to red for one second, and after this second the jbutton will return to normal. Cant make this work..
This is my Function
private void paint(final int num){
Timer timer = new Timer(500, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (num == 1){
btn.setBackground(Color.black);
}
}
});
timer.start();
}

Start a 500ms timer that will do two things when it goes off:
- change the color to red
- start a 1s timer that will change the color to normal, when it goes off

Well, this would do it (note, you would probably want to put the code from the first sleep onwards into a timer or it's own thread in a real application to avoid blocking the thread running the code):
public static void main(String[] args) throws Exception {
final JFrame jf = new JFrame();
final JButton jButton = new JButton("Hello");
final Color originalBackground = jButton.getBackground();
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
jf.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
jf.getContentPane().add(jButton);
jf.pack();
jf.setVisible(true);
}
});
Thread.sleep(500);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
jButton.setBackground(Color.RED);
}
});
Thread.sleep(1000);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
jButton.setBackground(originalBackground);
}
});

Two example clock window via multithreading/

I am trying to build a simple GUI clock with multithreading.My purpose is making two identical exampl clock window.
public class JavaApplication9 {
public static void main(String[] args) {
JFrame clock = new TextClockWindow();
clock.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
clock.setVisible(true);
}//end main}
class TextClockWindow extends JFrame {
private JTextField timeField; // set by timer listener
private JButton listener;
public TextClockWindow() {
// GUI
timeField = new JTextField(6);
timeField.setFont(new Font("sansserif", Font.PLAIN, 48));
JButton button1 = new JButton("Action");
add(button1);
button1.addActionListener((ActionListener) listener);
ActionListener listener=new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){setBackground(Color.red );
}
};
Container content = this.getContentPane();
content.setLayout(new FlowLayout());
content.add(timeField);
this.setTitle("My_simple_clock"); this.pack();
// Create a 1-second timer and action listener for it.
// Specify package because there are two Timer classes
javax.swing.Timer t = new javax.swing.Timer(1000,
new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Calendar now = Calendar.getInstance();
int h = now.get(Calendar.HOUR_OF_DAY);
int m = now.get(Calendar.MINUTE);
int s = now.get(Calendar.SECOND);
timeField.setText("" + h + ":" + m + ":" + s);
}
});
t.start();
}
This is code without multithreading.But wheni trying to use Runnable some error occured.
In method main Non Static variable cannot be referenced in a static context.
My code with multithreading:
public class MyClock{
public static void main(String[] args) {
Runnable r=new Clocks();
Thread n=new Thread(r);
n.start();
}
public class Clocks implements Runnable {
public Clocks() {}
public void run() {JFrame clock = new TextClockWindow();
clock.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
clock.setVisible(true);
}
please help find the reason why it is not work.runnable is writing correctly....

Is there a reason why you declared Clocks class as inner class ?
Move your Clocks class outside MyClock class and remove the public qualifier if you're declaring the class in the same file. It will start working.

My Swing application is likely not thread-safe - not sure why, though

Edited at the request of commenters. I hope this is compliant.
First post! Trying to understand why my Swing application will not advance from one panel to the next. Here is the general flow of the code :
public class MainWindow {
JFrame mainFrame;
ChangeablePanel currentScreen; // abstract and extends JPanel, has getters &
setters for a Timer (swing timer), a String (nextScreen), and an Image
(background image). also has a close(AWTEvent e) method that simply calls
"this.setVisible(false);"
public MainWindow() {
mainFrame = new JFrame("New Arcana");
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitleFrame();
} // MainFrame constructor
public void changeFrame(String frameType, String frameName) {
switch (frameType) {
case "Title":
setTitleFrame();
break;
case "Town":
setTownFrame(frameName);
break;
case "Movie":
setMovieFrame(frameName);
break;
default:
break;
} // switch
} // changeFrame
private void setTitleFrame() {
currentScreen = new TitlePanel();
currentScreen.addComponentListener(new ScreenChangeListener());
...
mainFrame.setContentPane(currentScreen);
mainFrame.setSize(titleScreenLength, titleScreenHeight); // put constants here if you want
mainFrame.setLocationRelativeTo(null);
mainFrame.setVisible(true);
} // setTitleFrame
private void setTownFrame(String townName) {
currentScreen = new TownPanel(townName);
currentScreen.addComponentListener(new ScreenChangeListener());
...
mainFrame.setContentPane(currentScreen);
mainFrame.setSize(townScreenLength, townScreenHeight); // put constants here if you want
mainFrame.setVisible(true);
} // setTownFrame
private void setMovieFrame(String movieName) {
currentScreen = new MoviePanel(movieName);
currentScreen.addComponentListener(new ScreenChangeListener());
...
mainFrame.setContentPane(currentScreen);
mainFrame.setSize(titleScreenLength, titleScreenHeight); // put constants here if you want
mainFrame.setVisible(true);
} // setMovieFrame
private class ScreenChangeListener implements ComponentListener {
#Override
public void componentHidden(ComponentEvent e) {
gotoNextScreen(e);
}
public void componentMoved(ComponentEvent e) {}
public void componentResized(ComponentEvent e) {}
public void componentShown(ComponentEvent e) {}
} // ScreenChangeListener
public void gotoNextScreen(ComponentEvent e) {
changeFrame(currentScreen.getNextScreen(), null);
}
} // MainWindow
public class Start {
...
public static void main(String[] args) {
initialize();
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new MainWindow();
}
});
} // main
...
} // Start
public class TitlePanel extends ChangeablePanel implements ActionListener {
JButton newGame, continueGame;
public TitlePanel() {
setFocusable(true);
...
newGame = new JButton("New Game");
continueGame = new JButton("Continue");
newGame.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
setNextScreen("Movie");
close(e);
}
});
add(newGame);
add(continueGame);
createTimer(10, this);
getTimer().start();
} // TitlePanel constructor
#Override
public void actionPerformed(ActionEvent e) {
repaint();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
drawTitleScreen(g2d);
} // paintComponent
private void drawTitleScreen(Graphics2D g2d) {
g2d.drawImage(getBGImage(), 0, 0, null);
newGame.setLocation(170, 550);
continueGame.setLocation(605, 550);
} // drawTitleScreen
} // TitlePanel
public class MoviePanel extends ChangeablePanel implements ActionListener {
public MoviePanel(String movieName) {
setFocusable(true);
addKeyListener(new AnyKeyActionListener());
...
createTimer(10, this);
getTimer().start();
} // TitlePanel constructor
#Override
public void actionPerformed(ActionEvent e) {
repaint();
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
drawMovie(g2d);
} // paintComponent
private void drawMovie(Graphics2D g2d) {
g2d.drawImage(getBGImage(), 0, 0, null);
} // drawTitleScreen
private class AnyKeyActionListener extends KeyAdapter {
public void keyTyped(KeyEvent e) {
setNextScreen("Town");
close(e);
} // keyPressed
} // listener to check for keystrokes
} // MoviePanel
The MainFrame is to be populated with more frames as the application advances based on user-input (currently, only MoviePanel and TownPanel are coded), and their code is fairly analogous to this one -- I pasted MoviePanel as well.
Execution breaks down after the KeyAdapter-based listener above. However, when I run my application in Debug mode in Eclipse with breakpoints, this indeed does what it's supposed to do and advances from the MoviePanel to the TownPanel. It is because of this that I suspect threading is the culprit here. Note that I did try many different combinations of the SwingUtilities.invokeLater() technique on the code-blocks above, but it didn't change anything. Any help would be appreciated; thanks!

Do the following:
invokeLater for creation ont the GUI Event Dispatch Thread
No repaint() during construction
setVisible last
Especially on event listeners again use invokeLater, to let buttons and such be responsive, and have then actions being taken with response too.
public static void main(String[] args) {
...
SwingUtilities.invokeLater() {
#Override()
new Runnable() {
new MainFrame().setVisible(true);
}
};
}
Code review
In TitlePanel.TitlePanel better use an absolute layout (that means null), instead of using setLocation in the painting code.
setLayout(null);
newGame = new JButton("New Game");
continueGame = new JButton("Continue");
newGame.setBounds(170, 550, 120, 24);
continueGame.setBounds(605, 550, 120, 24);
In ChangeablePanel.close ensure also timer.stop().
In MainWindow use invokeLater:
public void gotoNextScreen(ComponentEvent e) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
changeFrame(currentScreen.getNextScreen(), null);
}
});
}
In MoviePanel I cannot see that addKeyListener could function; maybe the left-out code? Or is this maybe the error you saw?
Furthermore I find a simple repaint() dubious; would have expected something like:
public void actionPerformed(ActionEvent e) {
invalidate();
repaint(10L);
}

Pausing a timerTask

I have hit another wall. After getting my key input working, I have been racking my brains for hours, i want to create a pause function, so that if the same key is pressed again the timertask stops running (i.e the game is paused)
JPanel component = (JPanel)frame.getContentPane();
component.getInputMap().put(KeyStroke.getKeyStroke("SPACE"), "space");
component.getActionMap().put("space", (new AbstractAction(){
public void actionPerformed(ActionEvent e){
Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask(){
public void run(){
grid.stepGame();
}
},250, 250);
}}));
}
The problem is i cant use a global boolean isRunning var and switch it each time the key is pressed because the timerTask method in a nested class (so the boolean isRunning would have to be declared final to be accessed...). Any ideas on how to detect if the key is pressed again or if the game is already running so i can pause/cancel my timerTask.
Many Thanks Sam

Since this is a Swing game, you should be using a javax.swing.Timer or Swing Timer and not a java.util.Timer. By using a Swing Timer, you guarantee that the code being called intermittently is called on the EDT, a key issue for Swing apps, and it also has a stop method that pauses the Timer. You can also give your anonymous AbstractAction class a private boolean field to check if the key is being pressed for the first time or not.
Also, kudos and 1+ for using Key Bindings instead of a KeyListener.
e.g.,
JPanel component = (JPanel) frame.getContentPane();
component.getInputMap().put(KeyStroke.getKeyStroke("SPACE"), "space");
component.getActionMap().put("space", (new AbstractAction() {
private boolean firstPress = true;
private int timerDelay = 250;
private javax.swing.Timer keyTimer = new javax.swing.Timer(timerDelay , new ActionListener() {
// Swing Timer's actionPerformed
public void actionPerformed(ActionEvent e) {
grid.stepGame();
}
});
// key binding AbstractAction's actionPerformed
public void actionPerformed(ActionEvent e) {
if (firstPress) {
keyTimer.start();
} else {
keyTimer.stop();
}
firstPress = !firstPress;
}
}));
Another useful option is to perform a repeating task on key press and stop it on key release, and this can be done easily by getting the keystrokes for on press and on release:
KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, true) // for key release
KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, false) // for key press
For example:
import java.awt.event.*;
import javax.swing.*;
public class SwingTimerEg2 {
private JFrame frame;
private Grid2 grid = new Grid2(this);
private JTextArea textarea = new JTextArea(20, 20);
private int stepCount = 0;
public SwingTimerEg2() {
frame = new JFrame();
textarea.setEditable(false);
frame.add(new JScrollPane(textarea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
setUpKeyBinding();
}
void setUpKeyBinding() {
final int timerDelay = 250;
final Timer keyTimer = new Timer(timerDelay, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
grid.stepGame();
}
});
JPanel component = (JPanel) frame.getContentPane();
final int condition = JComponent.WHEN_IN_FOCUSED_WINDOW;
final String spaceDown = "space down";
final String spaceUp = "space up";
component.getInputMap(condition).put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, false), spaceDown);
component.getActionMap().put(spaceDown, (new AbstractAction() {
public void actionPerformed(ActionEvent e) {
keyTimer.start();
}
}));
component.getInputMap(condition).put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0, true), spaceUp);
component.getActionMap().put(spaceUp, (new AbstractAction() {
public void actionPerformed(ActionEvent e) {
keyTimer.stop();
}
}));
}
public void doSomething() {
textarea.append(String.format("Zap %d!!!%n", stepCount));
stepCount ++;
}
private static void createAndShowGui() {
new SwingTimerEg2();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class Grid2 {
private SwingTimerEg2 stEg;
public Grid2(SwingTimerEg2 stEg) {
this.stEg = stEg;
}
void stepGame() {
stEg.doSomething();
}
}

Easiest and dirty solution:
final boolean[] isRunning = new boolean[1];
You don't want to do that—but it works assuming proper synchronization around.
What would be better is
final AtomicBoolean isRunning = new AtomicBoolean();
What would be even better is to review the design once again: global state usually means, "global problems"

The final qualifier requirement can easily be avoided -- replace your inner method (which has the final requirement) with a call to a class method.

No you got the wrong idea about WHY you need final for anonymous classes! Final is only needed for local variables (well more exactly any variable that might have a live time shorter than the given object).
Hence a static variable in a class is perfectly fine and will work perfectly!
Edit: example:
public class Main {
interface Test {
void call();
}
public static volatile boolean running = true;
public static void main(String[] args) {
Test t = new Test() {
#Override
public void call() {
System.out.println(Main.running);
}
};
t.call();
running = false;
t.call();
}
}

Keep a reference to the Timer somewhere, say in your game class.
When the game is paused cancel the Timer.
This will cancel any currently scheduled tasks.
Then when the game is unpaused schedule the timer again as you have done above.
public class Game {
private Timer timer;
public void pause() {
if (timer != null) {
timer.pause();
}
}
public void startOrResumeGame() {
if (timer == null) {
timer = new Timer();
} else {
// Just in case the game was already running.
timer.cancel();
}
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {
grid.stepGame();
}
}, 250, 250);
}
}

How can I repaint a label while doing some processing, in Swing?

I'm new to Swing and I was trying to do this:
On pressing a JButton, the program will start iterating over hundreds of items, taking 1 second to process each one, and after finishing each one he should update a label to show the number of items already processed.
The problem is, the label's text is not updated until the cycle finishes iterating over all the items.
I searched online and apparently it's because this is running in the same thread, so I created a new thread to process the data and to update the variable to be used in the label (number of processed files).
But it didn't work. Then I even made another thread, which I start after the previous one, that just repaints the label. Still nothing works.
The code is like this:
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try { SwingUtilities.invokeLater(validateFiles); }
}); }
Runnable validateFiles = new Runnable() {
#Override
public void run() {
while(x_is_not_100) {
processLoadsOfStuff();
label.setText(x); }
}
};
Can you help me with this?

Simple - use a SwingWorker. For more information, read the Tasks that Have Interim Results tutorial.
Here's a pretty generic example that will use a JLabel to display counting from 0 to 30 -
public final class SwingWorkerDemo {
private static JLabel label =
new JLabel(String.valueOf(0), SwingConstants.CENTER);
public static void main(String[] args){
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run() {
createAndShowGUI();
}
});
JLabelSwingWorker workerThread = new JLabelSwingWorker();
workerThread.run();
}
private static void createAndShowGUI(){
final JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(label);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private static class JLabelSwingWorker extends SwingWorker<Void, Integer>{
#Override
protected Void doInBackground() throws Exception {
for(int i = 1; i < 31; i++){
Thread.sleep(1000);
publish(i);
}
return null;
}
#Override
protected void process(List<Integer> integers) {
Integer i = integers.get(integers.size() - 1);
label.setText(i.toString());
}
}
}

The background processing must be done in a separate thread. But the label update must be done in the event dispatch thread.
So your code should look like this:
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
// start a new thread for the background task
new Thread(validateFiles).start();
});
}
Runnable validateFiles = new Runnable() {
#Override
public void run() {
while(x_is_not_100) {
processLoadsOfStuff();
// use SwingUtilities.invokeLater so that the label update is done in the EDT:
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
label.setText(x);
}
});
}
};
But you might want to use the SwingWorker class, which is designed to do that in a simpler way. Its documentation is very well done and contains examples.