Java语言程序设计基础篇

*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{
  	@Override
  	public 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 {
  			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 {
  			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);
  	}
  }
  

  • 输出结果：