I've seen this but it doesn't work for my code. This is my unique class:
public static void main(String[] args) {
try {
Main window = new Main();
window.open();
} catch (Exception e) {
e.printStackTrace();
}
}
public void open() {
Display display = Display.getDefault();
createContents();
shell.open();
shell.layout();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
}
protected void createContents() {
shell = new Shell(SWT.CLOSE | SWT.MIN | SWT.TITLE | SWT.ON_TOP);
shell.setSize(301, 212);
shell.setText("MyShell");
// ...Other contents...
btn = new Button(shell, SWT.NONE);
btn.setBounds(114, 151, 76, 25);
btn.setText("BUTTON!");
btn.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
doSomething();
}
});
}
The method doSomething() is a caller for another method, like this:
private void doSomething()
{
Thread th = new Thread() {
public void run() {
threadMethod();
}
};
th.start();
}
When I click my button, an "Invalid Thread Access" raises from Thread-0, and it points to the first instruction of threadMethod() (wich doesn't access to UI widgets). I've tried to surround my button listener with
Display.getDefault().asyncExec(new Runnable() {
public void run() {
// ...
}
});
but it doesn't work either. I need the doSomething() method because it checks some code before creating the thread.
This is threadMethod()
private void threadMethod()
{
String[] listItems = list.getItems();
String fileName;
Path source, target;
File folder = new File(dir + File.separator);
if (!folder.exists()) {
folder.mkdir();
}
try
{
for(int i = 0; i < list.getItemCount(); i++)
{
// do something with non UI widgets
}
list.removeAll();
}
catch(IOException | InterruptedException e)
{
//print error
}
}
Why I've got Invalid thread access? Thank you!
List is an SWT widget and if you call the getItems() method on it outside of the UI Thread (in this case your main thread), you get an ERROR_THREAD_INVALID_ACCESS SWTException. This is defined in the List API: ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
The Thread that created the receiver, is the the thread that created the Display. If a Display does not exist, the first call to Display.getDefault() creates one. Therefore your main thread, which calls the open() method, is the UI thread. Your code will work if you wrap the contents of the threadMethod():
private void threadMethod() {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
// threadMethod contents
}
});
}
It will then be executed in the UI thread.
Related
I am writing a turn-based game on the internet. I try to pop up a window that should be in front until the input stream is ready. I created smth like this, but it seems that it does not work.
class CustomBlockerDialog extends JDialog {
/**
*
*/
private static final long serialVersionUID = 1L;
public CustomBlockerDialog(Frame owner, String text) {
super(owner, true);
setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
setSize(300, 100); // Adjust if needed
setTitle("");
add(new JLabel(text, SwingConstants.CENTER));
}
}
final CustomBlockerDialog block = new CustomBlockerDialog(null, "Not your turn");
SwingUtilities.invokeLater(new Runnable() {//A
#Override
public void run() {
System.out.println("show");
block.setVisible(true);
}
});
boolean one_write_only = true;
while(in.ready()){ /* C*/
if(one_write_only){
System.out.println("waiting server");
one_write_only = false;
}
};
System.out.println("suppose to hide");
SwingUtilities.invokeLater(new Runnable() {//B
#Override
public void run() {
System.out.println("hide");
block.setVisible(false);
}
});
It looks like "A" and "B" are executed after "C" and I have no idea why.
Your problem must be due to "C" being called on the Swing event thread and not in a background thread, since it sounds like "C" is blocking the event thread from running "A". Solution: be sure that "C" is not called on the Swing event thread. Also if this is the case, and this can be tested by running the SwingUtilities.isEventDispatchThread() method, then you don't need all those other runnables.
// note that this all must be called on the Swing event thread:
final CustomBlockerDialog block = new CustomBlockerDialog(null, "Not your turn");
System.out.println("show");
// block.setVisible(true); // !! no this will freeze!
final SwingWorker<Void, Void> worker = new SwingWorker<>() {
public void doInBackground() throws Exception {
boolean one_write_only = true;
while(in.ready()){ /* C*/
if(one_write_only){
System.out.println("waiting server");
one_write_only = false;
}
}
}
}
worker.addPropertyChangeListener(new PropertyChangeListener() {
public void propertyChanged(PropertyChangeEvent pcEvt) {
if (pcEvt.getNewValue() == SwingWorker.StateValue.DONE) {
System.out.println("hide");
block.setVisible(false);
// call worker's get() method here and catch exceptions
}
}
});
worker.execute();
// moved to down here since the dialog is modal!!!
block.setVisible(true);
Caveat: code not compiled nor tested. There may be errors present as it was typed off the cuff.
Thanks to Hovercraft Full Of Eels, I created a little different solution which works in my case:
final SwingWorker<Object,Object> worker2 = new SwingWorker<Object, Object>() {
public Object doInBackground() throws Exception {
boolean one_write_only = true;
while(!in.ready()){ /* C*/
if(one_write_only){
System.out.println("waiting server");
one_write_only = false;
}
}
return one_write_only;
}
protected void done() {
try {
block.setVisible(false);
} catch (Exception ignore) {}
}
};
worker2.execute();
block.setVisible(true);
I have a method like below.
ProgressWindow is a sub class of JFrame containing JProgressBar.
addProgress() increments a value in the JProgressBar.
If I call this method from a method in another class, a frame of ProgressWindow will show up but not JProgressBar and some JLabels inside the frame. They show up after the last line (System.out.println("finish")).
If I call this method in a main method in the class containing this method, then every component (Bar, labels...) instantly shows up.
What can I do for showing the window correctly?
static void search(){
ProgressWindow window = new ProgressWindow();
window.setVisible(true);
ExecutorService execs = Executors.newFixedThreadPool(Runtime
.getRuntime().availableProcessors());
Collection<Callable<Void>> processes = new LinkedList<>();
for (int i = 0; i < 100; i++) {
processes.add(new Callable<Void>() {
#Override
public Void call() throws Exception {
progressWindow.addProgress(); // increment progress value
return null;
}
});
}
try {
execs.invokeAll(processes);
} catch (Exception e) {
e.printStackTrace();
} finally {
execs.shutdown();
}
System.out.println("finish");
The main problem is you seem to be calling search from the context of the Event Dispatching Thread.
The problem occurs because you are using execs.invokeAll which blocks until all the callables have finished running.
This means that the EDT is unable to process new events in Event Queue, including repaint events, this is why your UI is coming to a stand still...
There are a number of issues you are now going to face...
You should never update/modify a UI component from any thread other than the EDT
You should block the EDT for any reason
You seem to want to know when the search is complete, so you know need some kind of event notification...
The first thing we need is some way to be notified that the search has completed, this means you can no longer rely on search returning when the search is complete...
public interface SearchListener {
public void searchCompleted();
}
Next we need an intermeditate search method that builds the UI and ensure that the search is launched within it's own Thread...
static void search(final SearchListener listener) {
final ProgressWindow window = new ProgressWindow();
window.setVisible(true);
Thread t = new Thread(new Runnable() {
#Override
public void run() {
search(listener, window);
}
});
t.start();
}
Then we need to modify the original search method to utilise the SearchListener interface to provide notification when the search is complete...
static void search(final SearchListener listener, final ProgressWindow window){
ExecutorService execs = Executors.newFixedThreadPool(Runtime
.getRuntime().availableProcessors());
Collection<Callable<Void>> processes = new LinkedList<>();
for (int i = 0; i < 100; i++) {
processes.add(new Callable<Void>() {
#Override
public Void call() throws Exception {
// This method needs to ensure that
// what ever it does to the UI, it is done from within
// the context of the EDT!!
progressWindow.addProgress();
return null;
}
});
}
try {
execs.invokeAll(processes);
} catch (Exception e) {
e.printStackTrace();
} finally {
execs.shutdown();
}
System.out.println("finish");
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
listener.searchCompleted();
}
});
}
Now, without the source code for addProgress, I might be tempted to use
processes.add(new Callable<Void>() {
#Override
public Void call() throws Exception {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
progressWindow.addProgress();
}
});
return null;
}
});
}
Instead...
Take a look at Concurrency in Swing for more details
Sounds like you what you're wanting to do is invoke the setVisible on the Swing UI thread, you can do this with invokeAndWait or invokeLater.
So something like:
final ProgressWindow window = new ProgressWindow();
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
window.setVisible(true);
}
});
I'm designing a simple JavaFX form.
First, I load the JavaFX environment (and wait for it to finish), with something like this :
final CountDownLatch latch_l = new CountDownLatch(1);
try {
// init the JavaFX environment
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new JFXPanel(); // init JavaFX
latch_l.countDown();
}
});
latch_l.await();
}
This works fine. (the reason why I need to first load the JavaFX this way, is because it's mainly a Swing application, with some JavaFX components inside, but they are loaded later)
Now, I'd like to add a splash-screen on launch, and displays it while the JavaFX environment loads (and in fact put in on-screen for like 5 seconds, because there are logo, trademark etc.. of the application I need to show)
So I came up with a SplashScreen class, which just displays a JWindow on-screen, like that :
public class SplashScreen {
protected JWindow splashScreen_m = new JWindow();
protected Integer splashScreenDuration_m = 5000;
public void show() {
// fill the splash-screen with informations
...
// display the splash-screen
splashScreen_m.validate();
splashScreen_m.pack();
splashScreen_m.setLocationRelativeTo(null);
splashScreen_m.setVisible(true);
}
public void unload() {
// unload the splash-screen
splashScreen_m.setVisible(false);
splashScreen_m.dispose();
}
}
Now, I want for the splash-screen to load and display itself 5 seconds.
Meanwhile, I want the JavaFX environment to load, too.
So I updated the CountDownLatch like this :
final CountDownLatch latch_l = new CountDownLatch(2); // now countdown is set to 2
final SplashScreen splash_l = new SplashScreen();
try {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
// show splash-screen
splash_l.show();
latch_l.countDown();
// init the JavaFX environment
new JFXPanel(); // init JavaFX
latch_l.countDown();
}
});
latch_l.await();
splash_l.unload();
}
So, it's working, but the splash only stays for the JavaFX environment to load, so basically it unloads very quickly (which is normal, given the code I wrote).
How to display the splash-screen for 5 seconds minimum (if the JavaFX loads faster) without freezing the EDT ?
Thanks.
The most significant issue is you're blocking the Event Dispatching Thread, meaning that it can't display/update anything while it's blocked. The same problem applies to JavaFX.
You should, also, never update either from anything other then they respective event queues.
Now, there are any number of ways you might be able to go about this, but SwingWorker is probably the simplest for the time been.
I apologise, this is the entire exposure to JavaFX I've had...
public class TestJavaFXLoader extends JApplet {
public static void main(String[] args) {
new TestJavaFXLoader();
}
public TestJavaFXLoader() throws HeadlessException {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
Loader loader = new Loader();
loader.addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals("state") && evt.getNewValue().equals(SwingWorker.StateValue.DONE)) {
System.out.println("Load main app here :D");
}
}
});
loader.load();
}
});
}
public class Loader extends SwingWorker<Object, String> {
private JWindow splash;
private JLabel subMessage;
public Loader() {
}
protected void loadSplashScreen() {
try {
splash = new JWindow();
JLabel content = new JLabel(new ImageIcon(ImageIO.read(...))));
content.setLayout(new GridBagLayout());
splash.setContentPane(content);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
subMessage = createLabel("");
splash.add(createLabel("Loading, please wait"), gbc);
splash.add(subMessage, gbc);
splash.pack();
splash.setLocationRelativeTo(null);
splash.setVisible(true);
} catch (IOException ex) {
ex.printStackTrace();
}
}
protected JLabel createLabel(String msg) {
JLabel message = new JLabel("Loading, please wait");
message.setForeground(Color.CYAN);
Font font = message.getFont();
message.setFont(font.deriveFont(Font.BOLD, 24));
return message;
}
public void load() {
if (!EventQueue.isDispatchThread()) {
try {
SwingUtilities.invokeAndWait(new Runnable() {
#Override
public void run() {
loadSplashScreen();
}
});
} catch (Exception exp) {
exp.printStackTrace();
}
} else {
loadSplashScreen();
}
execute();
}
#Override
protected void done() {
splash.dispose();
}
#Override
protected void process(List<String> chunks) {
subMessage.setText(chunks.get(chunks.size() - 1));
}
#Override
protected Object doInBackground() throws Exception {
publish("Preparing to load application");
try {
Thread.sleep(2500);
} catch (InterruptedException interruptedException) {
}
publish("Loading JavaFX...");
runAndWait(new Runnable() {
#Override
public void run() {
new JFXPanel();
}
});
try {
Thread.sleep(2500);
} catch (InterruptedException interruptedException) {
}
return null;
}
public void runAndWait(final Runnable run)
throws InterruptedException, ExecutionException {
if (Platform.isFxApplicationThread()) {
try {
run.run();
} catch (Exception e) {
throw new ExecutionException(e);
}
} else {
final Lock lock = new ReentrantLock();
final Condition condition = lock.newCondition();
lock.lock();
try {
Platform.runLater(new Runnable() {
#Override
public void run() {
lock.lock();
try {
run.run();
} catch (Throwable e) {
e.printStackTrace();
} finally {
try {
condition.signal();
} finally {
lock.unlock();
}
}
}
});
condition.await();
// if (throwableWrapper.t != null) {
// throw new ExecutionException(throwableWrapper.t);
// }
} finally {
lock.unlock();
}
}
}
}
}
I found the runAndWait code here
Question:
Can you show any simple example or explanation of SWT display part(which updates the window/shell)? Or can you any sites that you think they are the best for SWT application development?
Background:
I am new to SWT application and currently building an application for running some tests.
It has a main display shell class with text area which keeps getting updated after user clicked on a run button.
The run button starts another thread process which updates public static object such as AtomicCounter in the StartView class.
Current Stage
The program seems running well, however, it does not update the text area in realtime.
Well, I can't say realtime but it shows a little bit delayed information.(I can say it's delayed because I print out on the console as well)
It seems like I don't understand displaying concept of SWT well enough to do whatever I am trying to do with it.
Goal
A. Main Display class which starts and stops C regardless of B running or not
B. Threaded process which updates text area of A class with public static object of A
C. Threaded process which does its job and updating public static object of A
Example Code (Working Code)
public class UnitTest {
public static Display display;
private Shell shell;
public static AtomicInteger counter = new AtomicInteger(0);
public static Text text;
private TestThread test1 = null, test2 = null;
public UnitTest()
{
display = Display.getDefault();
this.shell = new Shell(display, SWT.CLOSE);
this.shell.setSize(226, 120);
text = new Text(shell, SWT.BORDER);
text.setBounds(10, 10, 199, 19);
Button btnStart = new Button(shell, SWT.NONE);
btnStart.addSelectionListener(new SelectionAdapter() {
#Override
public void widgetSelected(SelectionEvent arg0) {
test1 = new TestThread();
test1.start();
test2 = new TestThread();
test2.start();
}
});
btnStart.setBounds(10, 54, 94, 28);
btnStart.setText("Start");
Button btnStop = new Button(shell, SWT.NONE);
btnStop.addSelectionListener(new SelectionAdapter() {
#Override
public void widgetSelected(SelectionEvent arg0) {
test1.interrupt();
test2.interrupt();
counter.set(0);
}
});
btnStop.setBounds(115, 54, 94, 28);
btnStop.setText("Stop");
this.shell.open();
this.shell.layout();
this.shell.addListener(SWT.Close, new Listener(){
public void handleEvent(Event event)
{
shell.dispose();
}
});
while(!this.shell.isDisposed())
{
if(!display.readAndDispatch())
{
//text.setText(""+counter.get());
display.sleep();
}
}
}
public static void main(String[] args)
{
new UnitTest();
}
}
class TestThread extends Thread
{
public void run()
{
try
{
int i = 0;
while(i++ < 1000 && !this.isInterrupted() )
{
UnitTest.counter.getAndIncrement();
try {
TestThread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
break;
}
if(UnitTest.display.isDisposed())
return;
UnitTest.display.asyncExec(new Runnable() {
public void run() {
if (UnitTest.text.isDisposed())
return;
UnitTest.text.setText(""+UnitTest.counter.get());
}
});
}
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
System.out.println("Existing thread...");
}
}
}
You should carefully use UI updates from separate threads. Please, read this:
http://goo.gl/At8hC
In my GUI I have a PDF file creation operation. The operation can take up to 10-15 seconds to complete. When I start the operation, I attach a listener to it. The listener changes the cursor and disables the GUI, until the operation completes.
I would also like to add a progressbar, so the users will have a idea when it is going to complete.
Created a method startProgressBar() and called it from the start of the operation method.
See Below:
private void startSavePdfOperation() {
startProgressBar();
saveOp = new AplotSaveOperation(appReg.getString("aplot.message.SAVETOPDF"), "PDF", session);
saveOp.addOperationListener(new MyOperationListener(this) {
startProgressBar Method - See Below:
public void startProgressBar() {
Shell shell = new Shell(getShell());
shell.setSize(260, 120);
final ProgressBar bar = new ProgressBar(shell, SWT.SMOOTH);
bar.setBounds (20, 20, 200, 20);
shell.open();
final int maximum = bar.getMaximum();
new Thread(new Runnable() {
public void run() {
for (final int[] i = new int[1]; i[0] <= maximum; i[0]++) {
try {Thread.sleep (100);} catch (Throwable th) {}
if (Display.getDefault().isDisposed()) return;
Display.getDefault().asyncExec(new Runnable() {
public void run() {
if (bar.isDisposed ()) return;
bar.setSelection(i[0]);
}
});
}
}
}).start();
The code above created the ProgressBar. The issue is that the operation would end well before the progressbar indicator was close to ending.
Question: Is this because in the method I am creating a new thread and the indicator is updating according to the new thread and not the operation thread?
Question: Is it possible to create a new thread that watches the GUI thread and updates the progressbar accordingly?
Read a article suggesting using ProgressMonitorDialog with IRunnableWithProgress.
Method startProgressBar using ProgressMonitorDialog - see below:
public void startProgressBar() {
ProgressMonitorDialog dialog = new ProgressMonitorDialog(getShell());
try {
dialog.run(true, true, new IRunnableWithProgress(){
public void run(IProgressMonitor monitor) {
monitor.beginTask("Some nice progress message here ...", 100);
** getThread(); **
monitor.done();
}
});
}
catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void getThread() {
new Thread etc.. etc...
}
It seems that it will have the same issues with threading and updating as the code above.
Question: So now I am thinking can I just add or update the ProgressBar to my existing Listener
OperationListener Code - see below:
public abstract class MyOperationListener implements InterfaceAIFOperationListener {
AplotCreatePDFDialog w = null;
public MyOperationListener(AplotCreatePDFDialog win) {
w = win;
}
public void startOperation(String startMessage) {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
w.getShell().setCursor(new Cursor(Display.getCurrent(), SWT.CURSOR_WAIT));
w.recursiveSetEnabled(getShell(), getShell().getEnabled());
w.getShell().setEnabled(!getShell().getEnabled());
}
});
}
public void endOperation() {
try {
endOperationImpl();
}
finally {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
w.getShell().setCursor(new Cursor(Display.getCurrent(), SWT.CURSOR_ARROW));
w.recursiveSetEnabled(getShell(), true);
w.getShell().setEnabled(!getShell().getEnabled());
w.close();
}
});
}
}
abstract protected void endOperationImpl();
} // end class MyOperationListener
Thanks for any help you can give me with this.
EDIT
Baz, your answer below is exactly what the question asked, so thank you for answering.
But I am starting to think that what I am trying to do is not possible.
When my operation starts, I wanted the progress bar indicator to start and when my operation ended I wanted the indicator be at the end and the monitor would close.
I thought there might bee a way to use my listener to add the progressbar. Something like the following.
public void startOperation(String startMessage) {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
->monitor.beginTask("Creating PDF File(s)", IProgressMonitor.UNKNOWN);<-
w.getShell().setCursor(new Cursor(Display.getCurrent(), SWT.CURSOR_WAIT));
w.recursiveSetEnabled(getShell(), getShell().getEnabled());
w.getShell().setEnabled(!getShell().getEnabled());
}
});
}
public void endOperation() {
try {
->monitor.worked(1);<-
endOperationImpl();
}
finally {
Display.getDefault().asyncExec(new Runnable() {
public void run() {
w.getShell().setCursor(new Cursor(Display.getCurrent(), SWT.CURSOR_ARROW));
w.recursiveSetEnabled(getShell(), true);
w.getShell().setEnabled(!getShell().getEnabled());
->monitor.done();<-
w.close();
}
});
}
}
abstract protected void endOperationImpl();
} // end class MyOperationListener
But I am starting to see that the ProgressBar has to have some sort of measurement to display the indicator correctly.
I would be happy if the indicator just went back and forth and the monitor would close at the end of the operation.
Why not use ProgressMonitorDialog?
Here is a related answer from me showing a simple example.
This is what it looks like:
If you are not sure about the workload, use this code:
monitor.beginTask("Copying files", IProgressMonitor.UNKNOWN);
It will show the idle bar while running.