Java语言程序设计基础篇_编程练习题*15.3 (移动小球)

*15.3 (移动小球)

编写一个程序，在面板上移动小球。应该定义一个面板类来显示小球，并提供向左、向右、向上和向下移动小球的方法，如图15-24c所示。请进行边界检査以防止球完全移到视线之外

代码展示：编程练习题15_3MoveBall.java

package chapter_15;import javafx.application.Application;
import javafx.geometry.Insets;
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.scene.text.Text;
import javafx.stage.Stage;public class 编程练习题15_3MoveBall extends Application{@Overridepublic void start(Stage primaryStage) throws Exception {BorderPane borderPane = new BorderPane();Pane pane = new Pane();HBox hBox = new HBox();pane.setPadding(new Insets(10, 10, 10, 10));hBox.setAlignment(Pos.CENTER);Circle circle = new Circle(150, 150, 20);circle.setFill(Color.WHITE);circle.setStroke(Color.BLACK);pane.getChildren().add(circle);Button btLeft = new Button("Left");Button btRight = new Button("Right");Button btUp = new Button("Up");Button btDown = new Button("Down");Text text = new Text("下一个动作将越界！");btLeft.setOnMouseClicked(e->{borderPane.setTop(null);if(circle.getCenterX()-circle.getRadius()*2 <0) {borderPane.setTop(text);return;}circle.setCenterX(circle.getCenterX()-circle.getRadius());});btRight.setOnMouseClicked(e->{borderPane.setTop(null);if(circle.getCenterX()+circle.getRadius()*2 > borderPane.getWidth()) {borderPane.setTop(text);return;}circle.setCenterX(circle.getCenterX()+circle.getRadius());});btUp.setOnMouseClicked(e->{borderPane.setTop(null);if(circle.getCenterY()-circle.getRadius()*2 < 0) {borderPane.setTop(text);return;}circle.setCenterY(circle.getCenterY()-circle.getRadius());});btDown.setOnMouseClicked(e->{borderPane.setTop(null);if(circle.getCenterY()+circle.getRadius()*2 > borderPane.getHeight()) {borderPane.setTop(text);return;}circle.setCenterY(circle.getCenterY()+circle.getRadius());});hBox.getChildren().addAll(btLeft, btRight, btUp, btDown);borderPane.getChildren().add(pane);borderPane.setBottom(hBox);Scene scene = new Scene(borderPane, 300, 300);primaryStage.setTitle("编程练习题14_3Poker");primaryStage.setScene(scene);primaryStage.show();}public static void main(String[] args) {Application.launch(args);}
}