JavaFX 8 Dialog - javafx-8

Question

I'm implementing a document editor with JavaFX8 and e(fx)clipse and want to user to be informed when the export (write to disc) is ongoing. I'm using the main (GUI) Thread for this as I want to block the gui during this operation (which takes 2-3 seconds). During this operation I want to show a small popup to inform the user that the export is ongoing, nothing fancy.
#FXML
public void export() {
Dialog dialog = new Dialog();
dialog.setContentText("exporting ...");
dialog.show();
// some lenghty methods come here, ~equivalent to Thread.sleep(3000);
dialog.hide();
}
When I press the corresponding Button which invokes the export method, I get somehow two dialogs, one of them NOT closing and remaining open after the method has finished.
Does somebody has an idea what's happening here? I'm really interested in a simple solution, I don't need to have a progress bar etc..
Another possibility would be to show a wait-cursor before the operation starts and switching back to the default cursor after that. Unfortunately, this does also not seem to work. I understand that the UI is blocked during the "lengthty" operation, but I don't udnerstand why I cant change the UI before and after that operation....

Answer 1

Your example isn't very complete - however I would recommend using one of two approaches. However, you aren't putting the long process on a background thread which will FREEZE your app. You want to offload that process.
1) Use the ControlsFX Dialog which has a Progess Alert. Tie your work to either a Task or a Service and provide that to the alert. This will pop the alert up while the thread is active, and will automatically close it when done. If you have intermediary progress values, it can be used to update the progress bar.
Or if you don't want to use this dialog, you could do something like this:
Alert progressAlert = displayProgressDialog(message, stage);
Executors.newSingleThreadExecutor().execute(() -> {
try {
//Do you work here....
Platform.runLater(() ->forcefullyHideDialog(progressAlert));
} catch (Exception e) {
//Do what ever handling you need here....
Platform.runLater(() ->forcefullyHideDialog(progressAlert));
}
});
private Alert displayProgressDialog(String message, Stage stage) {
Alert progressAlert = new Alert(AlertType.NONE);
final ProgressBar progressBar = new ProgressBar();
progressBar.setMaxWidth(Double.MAX_VALUE);
progressBar.setPrefHeight(30);
final Label progressLabel = new Label(message);
progressAlert.setTitle("Please wait....");
progressAlert.setGraphic(progressBar);
progressAlert.setHeaderText("This will take a moment...");
VBox vbox = new VBox(20, progressLabel, progressBar);
vbox.setMaxWidth(Double.MAX_VALUE);
vbox.setPrefSize(300, 100);
progressAlert.getDialogPane().setContent(vbox);
progressAlert.initModality(Modality.WINDOW_MODAL);
progressAlert.initOwner(stage);
progressAlert.show();
return progressAlert;
}
private void forcefullyHideDialog(javafx.scene.control.Dialog<?> dialog) {
// for the dialog to be able to hide, we need a cancel button,
// so lets put one in now and then immediately call hide, and then
// remove the button again (if necessary).
DialogPane dialogPane = dialog.getDialogPane();
dialogPane.getButtonTypes().add(ButtonType.CANCEL);
dialog.hide();
dialogPane.getButtonTypes().remove(ButtonType.CANCEL);
}