Java SE (Java Platform, Standard Edition)

Hi there,

I am a little bit frustrated with the Preloader API...

After reading the tutorial here I still don't get it...

At the end I just copy and paste the code from section 9.3.4 (the long startup task example) and it still won't work.

After starting the application I only see some black screen flickering at the upper left

screen and then the main app shows up.

What I have done:

Using Netbeans 8.0 under Linux(Fedora20 64bit), JDK 1.8u5 ...

Here are the two classes - the main app :

import javafx.application.Application;
import javafx.application.Platform;
import javafx.application.Preloader.ProgressNotification;
import javafx.application.Preloader.StateChangeNotification;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.SimpleBooleanProperty;
import javafx.beans.value.ObservableValue;
import javafx.concurrent.Task;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.stage.Stage;

public class PreloaderDemo extends Application {

 Stage stage;
 BooleanProperty ready = new SimpleBooleanProperty( false );

 private void longStart() {
 //simulate long init in background
 Task<Void> task = new Task<Void>() {
 @Override
 protected Void call() throws Exception {
 int max = 10;
 for ( int i = 1; i <= max; i++ ) {
 Thread.sleep( 1000 );
 // Send progress to preloader
 notifyPreloader( new ProgressNotification( ( ( double ) i ) / max ) );
 }
 // After init is ready, the app is ready to be shown
 // Do this before hiding the preloader stage to prevent the 
 // app from exiting prematurely
 ready.setValue( Boolean.TRUE );

 notifyPreloader( new StateChangeNotification(
 StateChangeNotification.Type.BEFORE_START ) );

 return null;
 }
 };
 new Thread( task ).start();
 }

 @Override
 public void start( final Stage stage ) throws Exception {
 // Initiate simulated long startup sequence
 longStart();

 stage.setScene( new Scene( new Label( "Application started" ),
 400, 400 ) );

 // After the app is ready, show the stage
 ready.addListener( (ObservableValue<? extends Boolean> ov, Boolean t, Boolean t1) -> {
 if ( Boolean.TRUE.equals( t1 ) ) {
 Platform.runLater( stage::show );
 }
 } );;
 }
}

Here is the preloader :

import javafx.application.Preloader;
import javafx.scene.Scene;
import javafx.scene.control.ProgressBar;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

public class DemoPreloader extends Preloader {

 ProgressBar bar;
 Stage stage;
 boolean noLoadingProgress = true;

 private Scene createPreloaderScene() {
 bar = new ProgressBar( 0 );
 BorderPane p = new BorderPane();
 p.setCenter( bar );
 return new Scene( p, 300, 150 );
 }

 @Override
 public void start( Stage stage ) throws Exception {
 this.stage = stage;
 stage.setScene( createPreloaderScene() );
 stage.show();
 }

 @Override
 public void handleProgressNotification( ProgressNotification pn ) {
 //application loading progress is rescaled to be first 50%
 //Even if there is nothing to load 0% and 100% events can be
 // delivered
 if ( pn.getProgress() != 1.0 || !noLoadingProgress ) {
 bar.setProgress( pn.getProgress() / 2 );
 if ( pn.getProgress() > 0 ) {
 noLoadingProgress = false;
 }
 }
 }

 @Override
 public void handleStateChangeNotification( StateChangeNotification evt ) {
 //ignore, hide after application signals it is ready
 }

 @Override
 public void handleApplicationNotification( PreloaderNotification pn ) {
 if ( pn instanceof ProgressNotification ) {
 //expect application to send us progress notifications 
 //with progress ranging from 0 to 1.0
 double v = ( ( ProgressNotification ) pn ).getProgress();
 if ( !noLoadingProgress ) {
 //if we were receiving loading progress notifications 
 //then progress is already at 50%. 
 //Rescale application progress to start from 50% 
 v = 0.5 + v / 2;
 }
 bar.setProgress( v );
 }
 else if ( pn instanceof StateChangeNotification ) {
 //hide after get any state update from application
 stage.hide();
 }
 }
}

Can anyone re-run this?

On my machine I see only a little black flickering on the left upper screen and

then immediately the app is shown...

The only way I can get this to run is to set the custom preloader property in the Netbeans-project properties...

Is this the only way I can achieve this?

If you use a maven based project in Netbeans you did not got this option ...

Regards,

Olek