Question

我对编程比较陌生，而且我很挣扎。我非常感谢你的帮助。我试图制作一个简单的程序，用户可以使用数字1和1更改透明舞台上显示的点的Y坐标。 2键盘上的键，上下移动。问题是当按下键时，我在方法外部制作的Y值变量不会更新。我知道实际的方法本身是有效的，因为我运行了一个打印行测试......除了那个方法之外，我只是不能在其他任何地方获得更新的值。有什么建议？

package application;

import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

        //Program where the user can adjust the Y Coordinate of a dot by 
                     pressing 1 & 2 Keyboard Keys 

public class Main extends Application implements EventHandler<KeyEvent>  {


    double x = 680; //The X Value of Dot (Never Changes)
    double y = 380; //The Y Value of Dot (The value users can change)

    @Override
    public void start(Stage stage) {                                        

                    //Root Properties
        AnchorPane root = new AnchorPane(); 
        root.getChildren().addAll(dot(), display());            
        root.setStyle("-fx-background-color: null;");    

                    //Scene Properties

        Scene scene = new Scene(root,1369, 715);         
        scene.setOnKeyPressed(this);
        scene.setFill(null);    

                    //Stage Settings
        stage.initStyle(StageStyle.TRANSPARENT);           
        stage.setScene(scene);                          
        stage.show();
        stage.setAlwaysOnTop(true);

    }

    @Override
    //KeyEvent That Adjusts the Y Coordinate that Starts off at 380
    public void handle (KeyEvent event){

            KeyCode key = event.getCode();

            if (key == KeyCode.DIGIT1){y = y + 100;}
            if (key == KeyCode.DIGIT2){y = y - 100;}
            System.out.println(y); 
            //A test to see if the method actually works (it does)
            };


                    //Properties of the Dot
     public Text dot(){
         Text dot = new Text();
            dot.setText(".");
            dot.setFont(new Font (100));                
            dot.setFill(Color.RED);                 
            dot.setX(x);
            dot.setY(y);
            return dot;}

                    //Displays the Value of Y on the Screen
     public Text display(){
         Text display = new Text(Double.toString(y));
         display.setX(600);
         display.setY(300);

        return display;}

    public static void main(String[] args) {launch(args);}

}

Answer 1

除dot坐标外，您还需要将x, y作为 类字段。然后，您就可以通过handle()方法访问它并更改其位置：

public class Main extends Application implements EventHandler<KeyEvent> { Text dot; double x = 680; //The X Value of Dot (Never Changes) double y = 380; //The Y Value of Dot (The value users can change) @Override public void start(Stage stage) { //Root Properties AnchorPane root = new AnchorPane(); dot = dot(); root.getChildren().addAll(dot, display()); root.setStyle("-fx-background-color: null;"); //Scene Properties Scene scene = new Scene(root,1369, 715); scene.setOnKeyPressed(this); scene.setFill(null); //Stage Settings stage.initStyle(StageStyle.TRANSPARENT); stage.setScene(scene); stage.show(); stage.setAlwaysOnTop(true); } @Override //KeyEvent That Adjusts the Y Coordinate that Starts off at 380 public void handle (KeyEvent event){ KeyCode key = event.getCode(); if (key == KeyCode.DIGIT1){dot.setY(dot.getY() + 100);} if (key == KeyCode.DIGIT2){dot.setY(dot.getY() - 100);} System.out.println(y); //A test to see if the method actually works (it does) }; //Properties of the Dot public Text dot(){ Text dot = new Text(); dot.setText("."); dot.setFont(new Font(100)); dot.setFill(Color.RED); dot.setX(x); dot.setY(y); return dot;} //Displays the Value of Y on the Screen public Text display(){ Text display = new Text(Double.toString(y)); display.setX(600); display.setY(300); return display;} public static void main(String[] args) {launch(args);} }

JavaFX：为什么KeyEvent不会在方法之外返回数据

1 个答案: