import java.util.Random;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.beans.InvalidationListener;
import javafx.beans.Observable;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.layout.StackPane;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
import javafx.util.Duration;

public class JavaFXApplication43 extends Application {

    final int N = 2000;
    final int WIDTH = 1200;
    final int HEIGHT = 800;
    Random rand;
    
    public static void main(String[] args) {
        launch(args);
    }
    
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("JavaFX 2");
        
        StackPane root = new StackPane();
        rand = new Random();        
        
        final ObservableList<Rectangle> data = FXCollections.observableArrayList();
        
        for(int i = 0; i < N; i++){
            
            data.add(new Rectangle(1, 1));
        }
        
        
        Timeline t = new Timeline();
        
        t.getKeyFrames().addAll(
                
                new KeyFrame(Duration.ZERO),
                new KeyFrame(Duration.INDEFINITE)
        );
        
        t.playFromStart();
        
        t.currentTimeProperty().addListener(new InvalidationListener(){

            @Override
            public void invalidated(Observable arg0) {
        
                for(Rectangle r : data){
                    
                    double x = r.getTranslateX();
                    double y = r.getTranslateY();
                    
                    x += 2 * Math.signum(rand.nextInt());
                    y += 2 * Math.signum(rand.nextInt());
                                        
                    r.setTranslateX(x);
                    r.setTranslateY(y);
                }
            }        
        });
        
        root.getChildren().addAll(data);
        
        primaryStage.setScene(new Scene(root, WIDTH, HEIGHT));
        primaryStage.show();
    }
}