Bolinha.java

package edu.curso;

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class Bolinha extends Application {

	class Ponto {

		double x;
		double y;
		double velX = 5;
		double velY = 0;

	}

	@Override

	public void start(Stage primaryStage) throws Exception {

		Group grp = new Group();
		Scene scn = new Scene(grp);
		primaryStage.setScene(scn);

		Canvas canvas = new Canvas(640, 480);

		GraphicsContext ctx = canvas.getGraphicsContext2D();
		grp.getChildren().add(canvas);
		final Ponto p = new Ponto();
		new AnimationTimer() {

			@Override
			public void handle(long now) {

				ctx.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());
				ctx.setStroke(Color.DARKBLUE);
				ctx.setFill(Color.BLUE);
				ctx.beginPath();
				ctx.fillOval(p.x, p.y, 50, 50);
				p.x += p.velX;
				p.y += p.velY;
				if ((p.x > canvas.getWidth() - 51) && (p.y == 0)) {
					p.velX = 0;
					p.velY = 5;
				} else if ((p.y > canvas.getHeight() - 51) && (p.x > canvas.getWidth() - 51)) {
					p.velY = 0;
					p.velX = -5;
				} else if ((p.x == 0) && (p.y == 0)) {
					p.velX = 0;
					p.velY = 0;
				} else if ((p.x == 0) && (p.y > canvas.getHeight() - 51)) {
					p.velX = 0;
					p.velY = -5;
				}
				ctx.stroke();
			}
		}.start();

		primaryStage.setTitle("Animação com bolinha");
		primaryStage.show();

	}

	public static void main(String[] args) {
		Application.launch(Bolinha.class, args);
	}

}