JavaFX移动小球

package javaseniorprograme;

import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;

/**
 * 移动小球
 * @author 李安国
 */
public class Exercise15_03 extends Application{
    @Override
    public void start(Stage primaryStage){
        // 创建一个面板
        Pane pane = new Pane();
        // 创建一个HBox
        HBox hbox = new HBox();
        // 创建四个按钮
        Button bt1 = new Button("Left");
        Button bt2 = new Button("Right");
        Button bt3 = new Button("Up");
        Button bt4 = new Button("Down");
        hbox.setAlignment(Pos.CENTER); 
        hbox.setSpacing(10);
        hbox.getChildren().addAll(bt1,bt2,bt3,bt4);
        // 创建一个圆
        Circle circle = new Circle(50,50,25);
        // 设置轮廓颜色
        circle.setStroke(Color.BLACK); 
        // 设置填充色
        circle.setFill(Color.WHITE); 
        pane.getChildren().add(circle);
      
        // 创建一个BorderPane面板
        BorderPane bdpane = new BorderPane();
        bdpane.setCenter(pane);
        bdpane.setBottom(hbox);
        Scene scene = new Scene(bdpane,300,300);
          
        bt1.setOnAction(e->{circle.setCenterX(circle.getCenterX() > 0 ? circle.getCenterX() - 10 : scene.getWidth());});
        bt2.setOnAction(e->{circle.setCenterX(circle.getCenterX() < scene.getWidth()? circle.getCenterX() + 10 : 0);});
        bt3.setOnAction(e->{circle.setCenterY(circle.getCenterY() > 0 ? circle.getCenterY() - 10 : scene.getHeight());});
        bt4.setOnAction(e->{circle.setCenterY(circle.getCenterY() < scene.getHeight()? circle.getCenterY() + 10 : 0);});
        primaryStage.setTitle("Exercise15_03");
        primaryStage.setScene(scene);
        primaryStage.show();
        
    }
    public static void main(String[] args){
        launch(args);
    }

}