一个提示：您应该避免比较双精度值的完全相等
a == b。
只需对代码进行一些小的更改，您就已经可以使用：
package learn.javafx;import javafx.animation.Keyframe;import javafx.animation.Timeline;import javafx.application.Application;import javafx.event.ActionEvent;import javafx.event.EventHandler;import javafx.geometry.Bounds;import javafx.scene.Scene;import javafx.scene.layout.Pane;import javafx.scene.paint.Color;import javafx.scene.shape.Circle;import javafx.stage.Stage;import javafx.util.Duration;public class GamePractice extends Application { public static Circle circle; public static Pane canvas; @Override public void start(final Stage primaryStage) { canvas = new Pane(); final Scene scene = new Scene(canvas, 800, 600); primaryStage.setTitle("Game"); primaryStage.setScene(scene); primaryStage.show(); circle = new Circle(15, Color.BLUE); circle.relocate(100, 100); canvas.getChildren().addAll(circle); final Timeline loop = new Timeline(new Keyframe(Duration.millis(10), new EventHandler<ActionEvent>() { double deltaX = 3; double deltaY = 3; @Override public void handle(final ActionEvent t) { circle.setLayoutX(circle.getLayoutX() + deltaX); circle.setLayoutY(circle.getLayoutY() + deltaY); final Bounds bounds = canvas.getBoundsInLocal(); final boolean atRightBorder = circle.getLayoutX() >= (bounds.getMaxX() - circle.getRadius()); final boolean atLeftBorder = circle.getLayoutX() <= (bounds.getMinX() + circle.getRadius()); final boolean atBottomBorder = circle.getLayoutY() >= (bounds.getMaxY() - circle.getRadius()); final boolean atTopBorder = circle.getLayoutY() <= (bounds.getMinY() + circle.getRadius()); if (atRightBorder || atLeftBorder) { deltaX *= -1; } if (atBottomBorder || atTopBorder) { deltaY *= -1; } } })); loop.setCycleCount(Timeline.INDEFINITE); loop.play(); } public static void main(final String[] args) { launch(args); }}
