JavaFX ProgressBar for TabPane - javafx-2

Question

I am interested in showing a progressbar while i switch to a different tab on my main tabpane. The tabs on my tabpane takes sometime(5-10 sec) before actually appearing. I want the progressbar to appear while the tab switching is taking place.

Answer 1

Download the data in a separate Task<T>, where T is a type that encapsulates all the data. Set the content of the tab to a progress bar; register an onSucceeded handler with the Task which sets the content of the tab to the display of the data, then start the task.
So this will look something like:
final Tab tab = ... ;
final ProgressBar progressBar = new ProgressBar();
final Task<MyDataType> loadDataTask = new Task<MyDataType>() {
#Override
public MyDataType call() throws Exception {
// download data...
MyDataType result = ... ;
return result ;
}
};
tab.setContent(progressBar);
loadDataTask.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
#Override
public void handle(WorkerStateEvent event) {
MyDataType data = loadDataTask.getValue();
Node tabContent = ... ; // build tab content from data
tab.setContent(tabContent);
}
});
final Thread thread = new Thread(loadDataTask);
thread.setDaemon(true);
thread.start();
Do not update any UI elements that are part of the scene graph in the Task's call(...) method. If you can measure the progress of the data download and want to show it in the progressBar (instead of an indeterminate progress bar), you can do
progressBar.progressProperty().bind(loadDataTask.progressProperty());
and then in the Task's call method, call
updateProgress(amountDone, totalAmount);