JavaFX: Der Versuch, Dialog vor der Anwendung

Question

Der Code erscheinen:

import java.io.IOException; 
import java.util.Optional; 

/** 
* Version 0.8 
* @author htha9587 
* 7-7-16 
*/ 

import javafx.application.Application; 
import javafx.fxml.FXMLLoader; 
import javafx.scene.Scene; 
import javafx.scene.control.TextInputDialog; 
import javafx.scene.image.Image; 
import javafx.scene.image.ImageView; 
import javafx.scene.layout.BorderPane; 
import javafx.stage.Stage; 

public class ChatbotRunner extends Application 
{ 
    private Stage primaryStage; 
    private BorderPane rootLayout; 
    /** 
    * Sets stage with the scene. 
    */ 
    @Override 
    public void start(Stage primaryStage) 
    { 
     //Sets up dialog before main application. 
     TextInputDialog dialog = new TextInputDialog("Harrison"); 
     dialog.setTitle("ChatbotFX"); 
     dialog.setHeaderText("This message brought to you by ChatbotFX."); 
     dialog.setContentText("What's your name?"); 
     dialog.initOwner(primaryStage); 
     //Sets Icon. 
     dialog.setGraphic(new ImageView(this.getClass().getResource("HAL.png").toString())); 
     //Retrieves response value. 
     Optional<String> result = dialog.showAndWait(); 
     if (result.isPresent()) 
     { 
      dialog.setResult("Hello " + result.get()); 
     } 

     //Sets main stage and scene. 
     this.primaryStage = primaryStage; 
     this.primaryStage.setTitle("ChatbotFX"); 

     //Sets Application Icon. 
     this.primaryStage.getIcons().add(new Image("file:resources/images/HAL.png")); 

     initRootLayout(); 
    } 

    public void initRootLayout() { 
     try { 
      // Load root layout from fxml file. 
      FXMLLoader loader = new FXMLLoader(ChatbotRunner.class.getResource("view/ChatbotView.fxml")); 
      rootLayout = (BorderPane) loader.load(); 

      // Show the scene containing the root layout. 
      Scene scene = new Scene(rootLayout); 
      primaryStage.setScene(scene); 
      primaryStage.show(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 

    /** 
    * Returns main stage. 
    */ 
    public Stage getPrimaryStage() 
    { 
     return primaryStage; 
    } 

    /** 
    * Runs the program. 
    * @param args 
    */ 
    public static void main(String[] args) 
    { 
     launch(args); 
    } 
} 

Meine Planung des Projekts ist dies: Haben Sie einen Text-Eingabedialog zeigen sich vor der Hauptanwendung und das Rück den Namen des Benutzers. Dann wird der Dialog geschlossen und die Hauptanwendung wird geöffnet.

Fehlermeldung:

Exception in Application start method 
java.lang.reflect.InvocationTargetException 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389) 
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767) 
Caused by: java.lang.RuntimeException: Exception in Application start method 
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917) 
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182) 
    at java.lang.Thread.run(Thread.java:745) 
Caused by: java.lang.NullPointerException 
    at javafx.scene.control.HeavyweightDialog.updateStageBindings(HeavyweightDialog.java:329) 
    at javafx.scene.control.HeavyweightDialog.initOwner(HeavyweightDialog.java:123) 
    at javafx.scene.control.Dialog.initOwner(Dialog.java:479) 
    at chat.ChatbotRunner.start(ChatbotRunner.java:37) 
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863) 
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326) 
    at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294) 
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95) 
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) 
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191) 
    ... 1 more 
Exception running application chat.ChatbotRunner 

Vielen Dank im Voraus.

Answer 1

Da die primäre Bühne nicht angezeigt wird, kann der Dialog sie nicht als Eigentümer verwenden. Dies wird ausgeführt, wenn Sie den Aufruf von initOwner() entfernen.