import javafx.animation.Animation;

import javafx.animation.KeyFrame;

import javafx.animation.Timeline;

import javafx.application.Application;

import javafx.event.ActionEvent;

import javafx.event.EventHandler;

import javafx.scene.Group;

import javafx.scene.Scene;

import javafx.scene.paint.Color;

import javafx.scene.shape.Circle;

import javafx.stage.Stage;

import javafx.util.Duration;

public class Main extends Application {

    static int dx = ;

    static int dy = ;

    public static void main(String[] args) {

        Application.launch(args);

    }

    @Override

    public void start(final Stage primaryStage) {

        primaryStage.setTitle("Animation");

        Group root = new Group();

        Scene scene = new Scene(root, , , Color.WHITE);

        primaryStage.setScene(scene);

        addBouncyBall(scene);

        primaryStage.show();

    }

    private void addBouncyBall(final Scene scene) {

        final Circle ball = new Circle(, , );

        final Group root = (Group) scene.getRoot();

        root.getChildren().add(ball);

        Timeline tl = new Timeline();

        tl.setCycleCount(Animation.INDEFINITE);

        KeyFrame moveBall = new KeyFrame(Duration.seconds(.),

                new EventHandler<ActionEvent>() {

                    public void handle(ActionEvent event) {

                        double xMin = ball.getBoundsInParent().getMinX();

                        double yMin = ball.getBoundsInParent().getMinY();

                        double xMax = ball.getBoundsInParent().getMaxX();

                        double yMax = ball.getBoundsInParent().getMaxY();

                        if (xMin <  || xMax > scene.getWidth()) {

                            dx = dx * -;

                        }

                        if (yMin <  || yMax > scene.getHeight()) {

                            dy = dy * -;

                        }

                        ball.setTranslateX(ball.getTranslateX() + dx);

                        ball.setTranslateY(ball.getTranslateY() + dy);

                    }

                });

        tl.getKeyFrames().add(moveBall);

        tl.play();

    }

}