choiceBoxを作成中にJavaFXのロード例外

Question

コントローラをロードしていくつかの選択ボックスを作成したいときに少し問題があります。 私は新しいステージを作成し、maincontrollerオブジェクトでシーンをロードしたいと思います。ここで

package simplygoals.control; 
import java.net.URL; 
import java.util.ResourceBundle; 
import javafx.beans.value.ChangeListener; 
import javafx.beans.value.ObservableValue; 
import javafx.event.ActionEvent; 
import javafx.fxml.FXML; 
import javafx.fxml.Initializable; 
import javafx.scene.control.Button; 
import javafx.scene.control.ChoiceBox; 
import javafx.scene.control.Label; 
import javafx.scene.control.Tooltip; 
import simplygoals.modelLogicComponents.User; 
import simplygoals.control.MainPanelController; 

public class RemoveUserController extends MainController implements Initializable { 
private MainPanelController mainControl; 
@FXML 
private ChoiceBox<User> UsersChoiceBox; 

@FXML 
private Label MessageLabel; 

@FXML 
private Button RemoveUsersButton; 

@FXML 
void f50303(ActionEvent event) { 

} 
boolean userRemoved=false; 
User removedUser=null; 
    @Override 
    public void initialize(URL location, ResourceBundle resources) { 
     choiceBoxInit(); 
    // observeChoiceBox(); 
    // removeUser(); 
    } 

    public void choiceBoxInit(){ 
     System.out.println(this.mainControl.getModelLogic()); 
    // UsersChoiceBox.setItems(this.mainControl.getModelLogic().getUserList()); 
    } 
    public void observeChoiceBox(){ 
     UsersChoiceBox.getSelectionModel().selectedIndexProperty().addListener(new ChangeListener<Number>(){ 
     public void changed(ObservableValue ov, Number value, Number new_value){ 
        if((new_value.intValue()>=0)&&(new_value.intValue()<=mainControl.getModelLogic().getUserList().size())){ 
         removedUser=mainControl.getModelLogic().getUserList().get(new_value.intValue()); 
        } 
     } 
     }); 
    } 
    public void removeUser(){ 
     RemoveUsersButton.setTooltip(new Tooltip("Select user")); 
     RemoveUsersButton.setOnAction(x->{ 

      String message = mainControl.getModelLogic().removeUserFromLogic(removedUser); 
      MessageLabel.setText("");    
      UsersChoiceBox.getItems().clear(); 
      UsersChoiceBox.setItems(mainControl.getModelLogic().getUserList()); 
      mainControl.updateComboBox(); 
     }); 
    } 

    public void setMainControl(MainPanelController mainPanel){ 
     mainControl=mainPanel; 
    } 

}

私は私のxmlファイルにインポートするものです：：

<?import javafx.scene.text.*?> 
<?import javafx.scene.control.*?> 
<?import java.lang.*?> 
<?import javafx.scene.layout.*?> 
<?import javafx.scene.layout.AnchorPane?> 

は助け

メインパネルをありがとうコントローラがあり

javafx.fxml.LoadException: 
/C:/Users/Kutti/workspace/SimplyGoals/bin/simplygoals/view/RemoveUser.fxml 

at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601) 
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2579) 
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441) 
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2409) 
at simplygoals.control.MainPanelController.lambda$2(MainPanelController.java:106) 
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86) 
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) 
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) 
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) 
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49) 
at javafx.event.Event.fireEvent(Event.java:198) 
at javafx.scene.Node.fireEvent(Node.java:8413) 
at javafx.scene.control.Button.fire(Button.java:185) 
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182) 
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96) 
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89) 
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218) 
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80) 
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) 
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) 
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) 
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) 
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54) 
at javafx.event.Event.fireEvent(Event.java:198) 
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757) 
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485) 
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762) 
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494) 
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:381) 
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295) 
at java.security.AccessController.doPrivileged(Native Method) 
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417) 
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389) 
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416) 
at com.sun.glass.ui.View.handleMouseEvent(View.java:555) 
at com.sun.glass.ui.View.notifyMouse(View.java:937) 
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) 
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191) 
at java.lang.Thread.run(Unknown Source) 
Caused by: java.lang.NullPointerException 
at simplygoals.control.RemoveUserController.choiceBoxInit(RemoveUserController.java:45) 
at simplygoals.control.RemoveUserController.initialize(RemoveUserController.java:39) 
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548) 
... 50 more 

コントローラクラス：

public class MainPanelController extends MainController implements Initializable { 

@FXML 
private TopPanelController topPanelController; 
public TopPanelController getTopPanelController() { 
    return topPanelController; 
} 

@FXML 
private MenuPanelController menuPanelController; 

@FXML 
private LeftPanelTimeModeController leftPanelTimeModeController; 

@FXML 
private CenterPanelTableController centerPanelTableController; 

@Override 
public void initialize(URL location, ResourceBundle resources) { 

    getModelLogic().createDB();//if there is no database create it, otherwise not 
    getModelLogic().updateUsers();//copy users from database to ModelLogic 
    updateComboBox(); 
    showAddUserPanel(); 
    showRemoveUserPanel(); 
    setUser(); 
    modelLogicToFile(); 

} 
public void updateComboBox(){ 
    ComboBox<String> comboBox = getTopPanelController().getUsersComboBox(); 

    comboBox.setOnMouseClicked(event->{ 
     comboBox.setItems(getModelLogic().getUsersObservableList());   
    }); 
} 
public void setUser(){ 
    ComboBox<String> comboBox = getTopPanelController().getUsersComboBox(); 
    comboBox.valueProperty().addListener(new ChangeListener<String>() { 
     @Override 
     public void changed(ObservableValue ov, String v1, String v2) {     
      if((v2!=null)){getModelLogic().setCurrentUser(v2);} 


     }  
    }); 
} 
public void showAddUserPanel(){ 
    Button button = getTopPanelController().getAddUserButton(); 
    button.setOnAction(event -> { 
         try { 
          FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("/simplygoals/view/AddUser.fxml")); 
          Parent root1 = (Parent) fxmlLoader.load(); 
          Stage stage = new Stage(); 
          stage.setResizable(false); 
          stage.setTitle("Add User"); 
          stage.setScene(new Scene(root1)); 
          AddUserController addUserController = fxmlLoader.getController(); 
          addUserController.setMainControl(this); 
          stage.show(); 
         } catch(Exception e) { 
          e.printStackTrace(); 
         } 
           }); 
} 
public void showRemoveUserPanel(){ 
    Button button = getTopPanelController().getRemoveUserButton(); 
    button.setOnAction(event -> { 
         try { 
          FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("/simplygoals/view/RemoveUser.fxml")); 
          Parent root2 = (Parent) fxmlLoader.load(); 
          Stage stage = new Stage(); 
          stage.setResizable(false); 
          stage.setTitle("Remove User"); 
          stage.setScene(new Scene(root2)); 
          RemoveUserController removeUserController = fxmlLoader.getController(); 
          removeUserController.setMainControl(this); 
          stage.show(); 
         } catch(Exception e) { 
          e.printStackTrace(); 
         } 
           }); 

} 

}

Answer 1

これはヌルポインタ例外の標準デバッグに過ぎません。

stack traceから明白にわかるように、RemoveUserController.choiceBoxInit()を呼び出すと、mainControlはnullです。このメソッドはRemoveUserController.initialize()から呼び出されます。

FXMLLoaderがFXMLファイルをロードするとき、つまりFXMLLoader.load(...)メソッドから呼び出されたとき、コントローラのinitialize()メソッドが呼び出されます。

FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("/simplygoals/view/RemoveUser.fxml")); 

// this line causes RemoveUserController.initialize() to be called: 
Parent root2 = (Parent) fxmlLoader.load(); 

Stage stage = new Stage(); 
stage.setResizable(false); 
stage.setTitle("Remove User"); 
stage.setScene(new Scene(root2)); 
RemoveUserController removeUserController = fxmlLoader.getController(); 

// mainControl is not initialized in removeUserController until you do this: 
removeUserController.setMainControl(this); 

したがって、あなたが呼ばれmainControlsetMainControlまでアクセスできません：あなたは（明らかに）あなたがload()後が完了したんsetMainController(...)メソッドを呼び出すまで

あなたはmainControlに値を割り当てないでください。

@Override 
public void initialize(URL location, ResourceBundle resources) { 
// choiceBoxInit(); 
// observeChoiceBox(); 
// removeUser(); 
} 

public void choiceBoxInit(){ 
    System.out.println(this.mainControl.getModelLogic()); 
// UsersChoiceBox.setItems(this.mainControl.getModelLogic().getUserList()); 
} 

// ... 

public void setMainControl(MainPanelController mainPanel){ 
    mainControl=mainPanel; 
    choiceBoxInit(); 
}