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Thread writting status update text on any components under mouse

This is a rather odd one. I am using a Swing button to launch a scan of a list of files. Because I want it to display updates on the status bar, I am using a Thread. Since Swing won't let anything draw until the button's code has finished, I am also using a Tread to allow me to change the 'Start Scan' button to a 'Stop Scan' button.
The problem is that if the wait cursor is placed over any other components, during the scan, the status messages are also being written onto those components, such as buttons (see sample button below code), check boxes, etc; which messes up the interface. Is this a major bug or is it not a good idea to do what I am doing? Is there a way around it?
private void jButton47ActionPerformed(java.awt.event.ActionEvent evt)
{
// Scan folders button.
//
this.getFrame().setCursor(new Cursor(Cursor.WAIT_CURSOR));
// If button is in stop mode then...
if (collection.isScanContinue())
{
collection.setScanContinue(false);
jButton47.setText(" Scan Folders For Files ");
jButton47.setBackground(view.getDefaultButtonCol());
}
else // in scan mode...
{
Thread t = new Thread(new Runnable()
{
#Override
public void run()
{
// Setup the stop scan process button (changes the scan button to a stop button).
//
collection.setScanContinue(true);
jButton47.setText(" Stop Scanning Folders ");
jButton47.setBackground(collection.getPrefs().getDeleteCol());
collection.scanSourceAndTargetFolders();
if(collection.isScanContinue())
{
// do scan
}
// Reset the stop scan button and flag.
//
collection.setScanContinue(false);
jButton47.setText(" Scan Folders For Files ");
jButton47.setToolTipText("Scans Source and, if required, Target folders.");
jButton47.setBackground(view.getDefaultButtonCol());
view.getFrame().setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
}
});
t.start();
}
}
It cleans up fine if I re-validate the main frame, but it looks terrible during the file scan.

Any action involving swing, such as changing button text etc, should be performed on event dispatch thread using SwingUtilities.invokeLater. Otherwise, you'll run into concurrency issues like you see here. See this question for more details about how event thread works: Java Event-Dispatching Thread explanation
Also, for doing background tasks like this, Swing provides a handy utility called SwingWorker: http://docs.oracle.com/javase/tutorial/uiswing/concurrency/worker.html

JavaFX 8 initialize method

So I am trying to do a chat type program using JavaFX for the GUI. I have it so a class that acts as a server will loop and keep adding client connections to it.
public void serverconnection()
{
// portnumber was saved from constructor
try (ServerSocket socket = new ServerSocket(this.portnumber))
{
// loop is a bool set to true
while (loop)
{
// this class extends Thread and has its own overwritten start method
new myclass(socket.accept()).start();
}
}
catch (IOException e)
{
System.exit(404);
}
}
so the problem is (I am assuming) was, this loop keeps looping until the program closes. but since I was calling this within the JavaFX's initialize method
public void initialize(URL url, ResourceBundle rb)
{
// constructor, nothing here is needed for this post
myclass z = new myclass(45234);
// problem here, since this has a loop, but
z.serverconnection();
// gui wont load till after this is done
// but serverconnection is only done after program ends
}
the problem with this is, apparently, the GUI will not load until AFTER initialize has finished, but it will not finish until program closes. After google searching, I could not find any fix for this. I need a way to call a method that will do all this, AFTER initialize method has finished. My client side class is similar to this, but the methods to connect on that are activated on events when clicking a login button. For this serverside one, I am trying to start without any interaction with the user. so is there a way to call a method or make this work AFTER initialize method has ran?

You might want to run this loop in a thread, so do something like
Thread t = new Thread(z::serverconnection)
t.start()
If you do this at the end of your initialization() method, it will run exactly then.
This will start a thread which runs forever; you might want to add a feature for interrupting the thread when the program is supposed to be terminated.
Remember that for changing anything in the GUI you need to sumbit a task via Platform.runLater(). This is because the GUI may only be modified from within that one thread. So in order to modify anything, you have to wrap that in a Runnable and submit it for execution.
You can do that in this way:
Platform.runLater(new Runnable() {
#Override
public void run() {
doWhateverNeedsToBeDone();
}
});
In Java 8, you can do anything of the following, depending on the extent of the work to be done:
Platform.runLater(() -> {
doWhateverNeedsToBeDone();
});
Platform.runLater(() -> doWhateverNeedsToBeDone());
Platform.runLater(this::doWhateverNeedsToBeDone);
The latter only works if doWhateverNeedsToBeDone() is a method of this.

showing progress of a task while a button is executing in java

I am executing several SQL queries in the function evoked by a button in java. I wish to show the status of the same, and I am using a jProgressBar for the same. But the problem is it will only update after the button has finished executing itself, making it pointless to show the progress. How can I display the actual progress of the executing button.

Make a thread dispatcher like this
public class ThreadDispatcher implements Runnable {
public ThreadDispatcher() {
}
public void run() {
//call the method related to query here
}
}
When button pressed call this class and let this class evoke your query related function.
It may be like this when you press the button.
Thread thread = new Thread(new ThreadDispatcher());
thread.start();
sleep(100);
catch the InterruptedException ex.
Link for Thread example

You need to do the computation on a background thread, not the main thread.
Take a look at the Java SwingWorker Tutorial.

Unable to change button text to icon immediate after click button in java swing

I have written following code.I have not shown full source but psudo code.
class UI extends JFrame
{
//created UI with one Button
onButtonclick()
{
//did some operation before set icon to button
//say opened fileopen dialog and get file
button.setText("");
ImageIcon progressbar = new
ImageIcon(DatasetExporterUI.class.getResource("/progreassbar.gif"));
buttonExport.setIcon(progressbar);
// did some database operations
//again removed icon from button
button.setIcon(null);
button.setText("click");
}
}
When I click on button It opens file open dialog and and button text get set to empty.
But It doesn't set Icon to button.When all Database operation are done which are performed after Icon set to button that time Icon is appeared on button.
Why this behavior is?
How to set Icon to button and do some Database operations and again remove it?
Thank you. :)

The GUI system can only do one thing at a time, like most code (except for code that uses threads). Calling your listener is a thing. The GUI system cannot do anything else while your listener is running.
Your database operation needs to run on another thread (which you can create) and then update the GUI when it's done. Something like this:
void onButtonPressed() {
// The code to open the file dialog goes here
button.setText("");
ImageIcon progressbar = new
ImageIcon(DatasetExporterUI.class.getResource("/progreassbar.gif"));
buttonExport.setIcon(progressbar);
new Thread() {
#Override
public void run() {
// do some database operations here
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
//again remove icon from button
button.setIcon(null);
button.setText("click");
}
});
}
}.start();
}
Code in different threads runs at the same time. This is convenient but dangerous. Be extremely careful when accessing data from the new thread - if one thread changes a field and the other thread reads it, the results might not be what you expect. The simplest thing to do is to make sure the main thread doesn't change any variables used by the new thread while it's running.
When your database operations are finished, you can't set the button back to normal by just calling setText. Only the main thread is allowed to affect the GUI - what if the main thread was drawing the button on the screen at the same time the database operation thread was changing the text? The button might be drawn incorrectly. So you need to call EventQueue.invokeLater which tells the GUI system to run your code in the near future when it's not busy. The code inside new Runnable() {} is like the code in the button listener - no other GUI-related code will run while it does.

This should work:
Image progressbar= ImageIO.read(DatasetExporterUI.class.getResource("/progreassbar.gif"));
buttonExport.setIcon(new ImageIcon(progressbar));

Applet with JDialog not hiding correctly in Mac OSX

I have an applet that calls a JDialog that contains a JProgressBar component. I subclass the JDialog to expose a method to update the JProgressBar, something like:
public class ProgressDialog extends javax.swing.JDialog {
public void setProgress(double progress) {
jProgressBar1.setValue(jProgressBar1.getMinimum() + (int) (progress * jProgressBar1.getMaximum()));
}
...
}
I use this dialog in the following manner:
public void test() throws Exception {
progressDialog = new ProgressDialog(null, true);
try {
progressDialog.setLocationRelativeTo(null);
// show the dialog
EventQueue.invokeLater(new Runnable() {
public void run() {
progressDialog.setVisible(true);
}
});
// business logic code that calls progressDialog.setProgress along the way
doStuff();
} finally {
progressDialog.setVisible(false);
progressDialog.dispose();
}
}
It works fine on Windows/any browser. However, when invoking the above function on Firefox 2/3/3.5 on a Mac, the progressDialog is displayed indefinitely, i.e. it doesn't close.
I suspected that calling setVisible(true) inside the EventQueue was causing the problem, since it's a blocking call and might block the queue completely, so I tried changing it to:
// show the dialog
new Thread() {
public void run() {
progressDialog.setVisible(true);
}
}.start();
With this change, the progressDialog now closes correctly, but a new problem emerged - the contents of the dialog (which included the progressbar, an icon and a JLabel used to show a message string) were no longer shown inside the dialog. It was still a problem only on Mac Firefox.
Any ideas? I realize it's probably some AWT threading issue, but I've been at this for a couple of days and can't find a good solution. Wrapping the doStuff() business logic in a separate new Thread seems to work, but it's not easy to refactor the actual business logic code into a separate thread, so I'm hoping there's a simpler solution.
The envt is:
Mac OSX 10.5
Java 1.5
Firefox 2/3/3.5

Found out that the problem was that the applet function was executing inside the AWT dispatcher thread, therefore the thread blocks and no events are processed until the applet function finishes execution.
Solution was to move the processing logic into a separate thread spawned by the ProgressDialog object before calling setVisible(true). setVisible(true) would block the main thread but still allow the event dispatcher to continue processing, hence rendering the contents of the dialog until the spawned thread calls setVisible(false) to hide the dialog.