我正在为我的班级使用 java 在 JGrasp 中制作一个神奇的 8 球。 如何让我的代码运行？ 我不知道我的错误是什么或如何解决它？

Question

这是我的代码

import java.util.*;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Rectangle;
import javafx.scene.shape.Polygon;
import javafx.scene.paint.Color;
import javafx.scene.text.Text;
import javafx.scene.image.ImageView;
import javafx.scene.image.Image;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.geometry.Pos;
import javafx.scene.layout.VBox;
import javafx.scene.control.Button;
import javafx.scene.layout.FlowPane;
import javafx.geometry.Pos;
import javafx.scene.control.TextField;
import java.security.SecureRandom;
import javax.swing.ImageIcon;
import javax.swing.JOptionPane;

   public class FinalProject8ball extends Application
   {
      @Override
      public void start(Stage primaryStage)
      {
         Circle circle = new Circle(80);
         circle.setStroke(Color.BLACK);
         circle.setFill(Color.BLACK);

         StackPane sPane = new StackPane();
         sPane.getChildren().add(circle);

         Scene scene = new Scene(sPane, 300, 400);
         primaryStage.setScene(scene);
         primaryStage.show();       
         Polygon triangle = new Polygon();
         triangle.getPoints().setAll(
            50.0, 50.0,
            60.0, 60.0,
            20.0, 40.0
            );

         StackPane sPane1 = new StackPane();
         sPane1.getChildren().add(triangle);

         Scene scene2 = new Scene(sPane, 300, 400);
         primaryStage.setScene(scene2);
         primaryStage.show();

         String answers[] = {"It is certain", "It is decidedly so", "Without a doubt",
            "Yes - definitely", "You may rely on it", "As I see it, yes",
            "Most likely", "Outlook good", "Signs point to yes",
            "Yes", "Reply hazy, try again", "Ask again later",
            "Better not tell you now", "Cannot predict now", "Concentrate and ask again",
            "Don't count on it", "My reply is no", "My sources say no",
            "Outlook not so good", "Very doubtful"};

        //constructs a random number  
         SecureRandom randomNumber = new SecureRandom();
         ImageIcon image = new ImageIcon("magic8ball.jpg");
         int counter = 0;

        //the loop keeps asking the person to plat till no button is clicked
         while(!(counter == 1)) {
            //prompts the user to ask a yes or no question 
            String answer = JOptionPane.showInputDialog(null, 
                    "PLease enter a yes or no question:", 
                    "WELCOME: What will your answer be?!", JOptionPane.INFORMATION_MESSAGE);

            //displays the answer
            if(answer != null)
               JOptionPane.showMessageDialog(null, answer+ "\n" + answers[randomNumber.nextInt(answers.length)], 
                  "The Magic-8 Ball has responded.", JOptionPane.PLAIN_MESSAGE, image);

            //gives the user the option to click yes or no to continue or end the program
            counter = JOptionPane.showConfirmDialog(null, "", "Would you like to ask again?", 
                    JOptionPane.YES_NO_OPTION, 0, image);                           
         }

        //displays my name after user enters no to give credit
         JOptionPane.showMessageDialog(null, "Created by Isabelle", "Have a MAGICAL day! Your answers have been answerd.", 
                JOptionPane.PLAIN_MESSAGE, image);
      }
      public static void main(String[] args)
      {
         Application.launch(args);
         }
      }

这是我在编译后尝试运行我的代码后得到的错误消息。

----jGRASP exec: java --module-path C:\\Users\\Isabelle rose\\Downloads\\openjfx-11.0.2_windows-x64_bin-sdk (1)\\javafx-sdk-11.0.2\\lib --add-modules =javafx.controls FinalProject8ball 异常在应用程序启动方法 java.lang.reflect.InvocationTargetException at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke( NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at javafx .graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464) 在 javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363) 在 java.base/jdk .internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 在 java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62 ) 在 java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 在 java.base/java.lang.reflect.Method.invoke(Method.java:566) 在 java.base/sun。 launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051) 引起：java.lang.RuntimeException：javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)处的应用程序启动方法异常) 在 javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195) 在 java.base/java.lang.Thread.run(Thread.java:834) 引起：java .lang.IllegalArgumentException: StackPane@4c7dc253[styleClass=root] 已经被设置为 javafx.graphics/javafx.scene.Scene$8.invalidated(Scene.java:1216) 的另一个场景的根。 property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112) 在 javafx.base/javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:147) 在 javafx.graphics/javafx.scene。 Scene.setRoot(Scene.java:1178) at javafx.graphics/javafx.scene.Scene.(Scene.java:356) at javafx.graphics/javafx.scene.Scene.(Scene.java:236) at FinalProject8ball.start (FinalProject8ball.java:58) 在 javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846) 在 javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$ runAndWait$12(PlatformImpl.java:455) 在 javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428) 在 java.base/java.security.AccessController.doPrivileged(Native Method) ) 在 javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427) 在 javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java: 96) 在 javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method) 在 javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java: 174) ... 1 个运行应用程序 F 的异常 inalProject8ball

Answer 1

堆栈中的真正错误如下：

Caused by: java.lang.IllegalArgumentException: StackPane@70ea261c[styleClass=root]is already set as root of another scene

看看这一行：

Scene scene2 = new Scene(sPane, 300, 400);

试试这个：

// You already used 'sPane' as the root of a previous scene called 'scene'
Scene scene2 = new Scene(sPane1, 300, 400);

笔记：

尽管您的程序将通过这个单一更改运行，但我认为您会发现它看起来不像它应该的样子。 您正在使用两个堆栈窗格，一个是圆形，另一个是三角形。 将堆栈窗格视为节点堆栈，每个节点一个层叠一个，就好像您在物理上堆叠它们一样。 可以肯定的是，您只需要一个带有圆圈和三角形的堆栈窗格即可代表一个 8 球。