JavaFX TreeView爲null爲什麼？

-1

我想將我的FXML文件中定義的TreeView加載到我的java代碼中的TreeView變量中。但總是當我嘗試它時，TreeView是NULL。JavaFX TreeView爲null爲什麼？

我到處看着Google，這裏有很多問題和答案，但沒有任何結果。

我需要TreeView動態添加TreeItems到它。

這裏放在src/rn.IconTool.view我IconOverview.FXML文件：

 <?xml version="1.0" encoding="UTF-8"?> 

<?import javafx.scene.image.*?> 
<?import javafx.scene.control.*?> 
<?import java.lang.*?> 
<?import javafx.scene.layout.*?> 
<?import javafx.scene.layout.AnchorPane?> 
<?import rn.IconTool.model.*?> 
<?import javafx.scene.control.TreeView?> 

<AnchorPane prefHeight="584.0" prefWidth="966.0" xmlns="http://javafx.com/javafx/8"     
         xmlns:fx="http://javafx.com/fxml/1" 
         fx:controller="rn.IconTool.model.IconOverviewControllerClass"> 
<children> 
    <SplitPane dividerPositions="0.229253112033195" layoutX="2.0" layoutY="34.0" prefHeight="547.0" prefWidth="966.0"> 
    <items> 
     <AnchorPane fx:id="splitPaneMenu" minHeight="0.0" minWidth="0.0" prefHeight="545.0" prefWidth="353.0"> 
      <children>        
       <TreeView fx:id="treeview" layoutX="-5.0" onMouseClicked="#ShowContextMenu" prefHeight="545.0" prefWidth="218.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0" /> 
      </children> 
     </AnchorPane> 
     <AnchorPane prefHeight="533.0" prefWidth="675.0"> 
      <children> 
      <AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="545.0" prefWidth="702.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0"> 
       <children> 
        <ImageView fitHeight="95.0" fitWidth="104.0" layoutX="22.0" layoutY="14.0" pickOnBounds="true" preserveRatio="true" /> 
       </children> 
       </AnchorPane> 
      </children> 
     </AnchorPane> 
    </items> 
    </SplitPane> 
    <ToolBar layoutY="-1.0" prefHeight="30.0" prefWidth="968.0" /> 
</children> 
</AnchorPane>

我RootLayout.fxml，位於.view太

 <?xml version="1.0" encoding="UTF-8"?> 

<?import javafx.scene.control.*?> 
<?import java.lang.*?> 
<?import javafx.scene.layout.*?> 
<?import javafx.scene.layout.BorderPane?> 
<?import rn.IconTool.model.*?> 


<BorderPane prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" 
xmlns:fx="http://javafx.com/fxml/1" fx:controller="rn.IconTool.model.NewCategoryClass"> 
<top> 
    <MenuBar BorderPane.alignment="CENTER"> 
    <menus> 
     <Menu mnemonicParsing="false" text="File"> 
     <items> 
      <MenuItem mnemonicParsing="false" text="Close" /> 
       <MenuItem mnemonicParsing="false" onAction="#NewtCategory" text="New Category" /> 
     </items> 
     </Menu> 
     <Menu mnemonicParsing="false" text="Edit"> 
     <items> 
      <MenuItem mnemonicParsing="false" text="Delete" /> 
     </items> 
     </Menu> 
     <Menu mnemonicParsing="false" text="Help"> 
     <items> 
      <MenuItem mnemonicParsing="false" text="About" /> 
     </items> 
     </Menu> 
    </menus> 
    </MenuBar> 
</top> 
</BorderPane>

的CreateNewCategoryScreen.fxml英寸鑑於太

 <?xml version="1.0" encoding="UTF-8"?> 

<?import javafx.scene.control.*?> 
<?import java.lang.*?> 
<?import javafx.scene.layout.*?> 
<?import javafx.scene.layout.BorderPane?> 
<?import rn.IconTool.model.*?> 


<BorderPane prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" 
xmlns:fx="http://javafx.com/fxml/1" fx:controller="rn.IconTool.model.NewCategoryClass"> 
    <top> 
    <MenuBar BorderPane.alignment="CENTER"> 
    <menus> 
     <Menu mnemonicParsing="false" text="File"> 
     <items> 
      <MenuItem mnemonicParsing="false" text="Close" /> 
       <MenuItem mnemonicParsing="false" onAction="#NewtCategory" text="New Category" /> 
     </items> 
     </Menu> 
     <Menu mnemonicParsing="false" text="Edit"> 
     <items> 
      <MenuItem mnemonicParsing="false" text="Delete" /> 
     </items> 
     </Menu> 
     <Menu mnemonicParsing="false" text="Help"> 
     <items> 
      <MenuItem mnemonicParsing="false" text="About" /> 
     </items> 
     </Menu> 
    </menus> 
    </MenuBar> 
    </top> 
</BorderPane>

而且我ContextMenuPane.fxml雖然地處.view：

 <?xml version="1.0" encoding="UTF-8"?> 

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


<AnchorPane prefHeight="254.0" prefWidth="166.0" xmlns:fx="http://javafx.com/fxml/1" 
xmlns="http://javafx.com/javafx/8"> 
<!-- TODO Add Nodes --> 
</AnchorPane>

這裏的控制器類，我試圖讓TreeView控件的src/rn.IconTool.model IconOverviewControllerClass：

 package rn.IconTool.model; 
    import java.io.IOException; 
    import rn.IconTool.MainApp; 
    import javafx.fxml.FXML; 
    import javafx.fxml.FXMLLoader; 
    import javafx.scene.control.ContextMenu; 
    import javafx.scene.control.TreeView; 
    import javafx.scene.input.MouseEvent; 
    import javafx.scene.layout.AnchorPane; 

public class IconOverviewControllerClass { 

@FXML TreeView treeview; 
@FXML private AnchorPane splitPaneMenu; 

public IconOverviewControllerClass(){ 

} 

    @FXML 
    public void ShowContextMenu(MouseEvent r){ 

     GetInTouchWithContextMenu git = new GetInTouchWithContextMenu(); 


    //   treeview = (TreeView<String>) getScene().lookup("#treeview"); 


     if(r.getButton() == r.getButton().SECONDARY){ 
      System.out.println("Rechtsklick"); 

      ContextMenu contextM = git.getTheContextMenu(); 
      System.out.println(contextM.toString()); 

     //    treeview.setContextMenu(contextM); 
     //     
    //    contextM.show(treeview, r.getX(), r.getY()); 
    //    System.out.println(contextM.isShowing()); 

      System.out.println("X: " + r.getX() + " Y: " + r.getY());    
     } 

    } 



    public TreeView<?> getTreeView() throws IOException{ 

     FXMLLoader loader = new FXMLLoader(); 
     loader.setLocation(MainApp.class.getResource("view/IconOverview.fxml")); 
     AnchorPane iconOverview = (AnchorPane) loader.load(); 

     treeview = (TreeView<?>) iconOverview.lookup("#treeview"); 

     System.out.println("TreeIconOver: " + treeview + " iconOverView: " + iconOverview); 
     return treeview; 
    } 
}

我的類來創建一個ContextMenu什麼isn't工作，但沒有更糟。 SRC/rn.IconTool.model GetInTouchWithContextMenu：

 package rn.IconTool.model; 

import javafx.event.ActionEvent; 
import javafx.event.EventHandler; 
import javafx.scene.control.ContextMenu; 
import javafx.scene.control.MenuItem; 
import javafx.stage.WindowEvent; 



public class GetInTouchWithContextMenu { 

private ContextMenu contextM = null; 

public GetInTouchWithContextMenu(){ 
    getContextMenu(); 
} 



private void getContextMenu(){ 

    contextM = new ContextMenu(); 
    contextM.setOnShowing(new EventHandler<WindowEvent>() { 
     public void handle(WindowEvent e) { 
      System.out.println("showing"); 
     } 
    }); 


    contextM.setOnShown(new EventHandler<WindowEvent>() { 
     public void handle(WindowEvent e) { 
      System.out.println("shown"); 
     } 
    }); 



    MenuItem item1 = new MenuItem("About"); 
    item1.setOnAction(new EventHandler<ActionEvent>() { 
     public void handle(ActionEvent e) { 
      System.out.println("About"); 
     } 
    }); 


    contextM.getItems().addAll(item1); 

} 



public ContextMenu getTheContextMenu(){ 
    return contextM; 
} 
}

這裏是我的屏幕爲我的TreeView的src /新建TreeItems rn.IconTool.model NewCategoryClass

 package rn.IconTool.model; 


import java.io.IOException; 

import javafx.fxml.FXML; 
import javafx.fxml.FXMLLoader; 
import javafx.scene.Node; 
import javafx.scene.Scene; 
import javafx.scene.control.Button; 
import javafx.scene.control.TreeItem; 
import javafx.scene.control.TreeView; 
import javafx.scene.image.Image; 
import javafx.scene.image.ImageView; 
import javafx.scene.layout.AnchorPane; 
import javafx.stage.Stage; 
import rn.IconTool.MainApp; 

public class NewCategoryClass { 

private AnchorPane categoryPane; 
private Stage stage; 
private Scene scene; 
private Node rootIcon; 

@FXML private javafx.scene.control.Button closeButton; 
@FXML private javafx.scene.control.TextField categoryName; 
@FXML private javafx.scene.control.TextField categoryIconName; 
@FXML private javafx.scene.control.TreeView<String> treeview; 


public NewCategoryClass(){ 
    //System.out.println("Neue Kategorie erstellen."); 
} 


@FXML 
private void NewtCategory() throws IOException{ 
    System.out.println("Neue Kategorie angelegt."); 



    FXMLLoader loader = new FXMLLoader(); 
    loader.setLocation(MainApp.class.getResource("view/CreateNewCategoryScreen.fxml")); 
    categoryPane = (AnchorPane) loader.load(); 


    scene = new Scene(categoryPane); 

    closeButton = (Button) scene.lookup("#closeButton"); 

    stage = new Stage(); 
    stage.setTitle("Set New Category"); 
    stage.setScene(scene); 
    stage.show(); 

} 

@FXML 
private void FinishButtonlistener() throws IOException{ 
    // get a handle to the stage 
    Stage stage = (Stage) closeButton.getScene().getWindow(); 
    // do what you have to do 
    System.out.println("Textfeld: " + categoryName.getText()); 

    // leeres Textfeld = leerer String 
    TreeItem<String> rootItem; 
    if(categoryName.getText().equals("")){ 

    }else{ 
     if(categoryIconName.getText().equals("")){ 
      rootItem = new TreeItem<String> (categoryName.getText()); 
     }else{ 
      setRootIcon(categoryIconName.getText()); 
      rootItem = new TreeItem<String> (categoryName.getText(), getRootIcon()); 
     } 

     IconOverviewControllerClass iocc = new IconOverviewControllerClass(); 
     iocc.getTreeView(); 


     // treeview.setRoot(rootItem); 

     //System.out.println("AnchorPane: " + splitPaneMenu); 
     System.out.println("Treeview: " + treeview); 
     System.out.println("TreeItem: " + rootItem); 

     stage.close(); 
    } 
} 


private void setRootIcon(String iconName){ 
    rootIcon = new ImageView(new Image(this.getClass().getResourceAsStream(iconName))); 
} 


public Node getRootIcon(){ 
    return rootIcon; 
} 


public Stage getStage(){ 
    return stage; 
} 

public Scene getScene(){ 
    return scene; 
} 
}

我主要放在src/rn.IconTool

 package rn.IconTool; 

import java.io.IOException; 

import javafx.application.Application; 
import javafx.fxml.FXMLLoader; 
import javafx.scene.Scene; 
import javafx.scene.layout.AnchorPane; 
import javafx.scene.layout.BorderPane; 
import javafx.stage.Stage; 


public class MainApp extends Application { 

private Stage primaryStage; 
private BorderPane rootLayout; 
private AnchorPane iconOverview; 
private Scene scene; 

@Override 
public void start(Stage primaryStage) { 
    this.primaryStage = primaryStage; 
    this.primaryStage.setTitle("Icon Place"); 

    initRootLayout(); 

    showIconOverview(); 
} 

/** 
* Initializes the root layout. 
*/ 
public void initRootLayout() { 
    try { 
     // Load root layout from fxml file. 
     FXMLLoader loader = new FXMLLoader(); 
     loader.setLocation(MainApp.class.getResource("view/RootLayout.fxml")); 
     rootLayout = (BorderPane) loader.load(); 



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


public void showIconOverview() { 
    try { 

     FXMLLoader loader = new FXMLLoader(); 
     loader.setLocation(MainApp.class.getResource("view/IconOverview.fxml")); 
     iconOverview = (AnchorPane) loader.load(); 

     rootLayout.setCenter(iconOverview); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 


} 

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

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


public Scene getScene(){ 
    return scene; 
} 
}

我希望你們有人能幫助我

如果你需要其他類來構建完整的程序，然後問，但我希望你有一些想法，樹視圖不爲空;）

來源

2014-10-26 earny1989

我知道爲什麼我的TreeView是NULL。我忘了實現javafx.fxml.Initializable並添加未實現的方法。

這是我的新IconOverviewControllerClass和不要擔心靜態TreeView的是測試的目的;）

 package rn.IconTool.model; 

import java.io.IOException; 
import java.net.URL; 
import java.util.ResourceBundle; 

import javafx.fxml.FXML; 
import javafx.scene.control.ContextMenu; 
import javafx.scene.control.TreeView; 
import javafx.scene.input.MouseEvent; 
import javafx.scene.layout.AnchorPane; 



public class IconOverviewControllerClass implements javafx.fxml.Initializable{ 



@FXML public TreeView<String> treeview; 
@FXML private AnchorPane splitPaneMenu; 

private static TreeView<String> statictreeView; 

public IconOverviewControllerClass(){ 

} 



@FXML 
public void initMyComponents(MouseEvent r) throws IOException{ 
    if(getTreeView() == null){ 
     System.out.println(treeview); 
     statictreeView = treeview; 
     System.out.println("static init: " + statictreeView); 
    } 


    ShowContextMenu(r); 
} 


    public void ShowContextMenu(MouseEvent r){ 

     if(r.getButton() == r.getButton().SECONDARY){ 
      System.out.println("Rechtsklick"); 
      GetInTouchWithContextMenu git = new GetInTouchWithContextMenu(); 
      ContextMenu contextM = git.getTheContextMenu(); 
      System.out.println(contextM.toString()); 

      treeview.setContextMenu(contextM); 

      contextM.show(treeview, r.getX(), r.getY()); 
      System.out.println(contextM.isShowing()); 

      System.out.println("X: " + r.getX() + " Y: " + r.getY()); 
     } 

    } 



    public TreeView<String> getTreeView() throws IOException{ 
     return statictreeView; 
    } 



    @Override 
    public void initialize(URL location, ResourceBundle resources) { 
     //System.out.println(treeview); 
     statictreeView = treeview; 
    } 
}

來源

2014-10-29 11:15:50 earny1989

你不必查找樹視圖： treeview =（TreeView） iconOverview.lookup（「＃樹視圖」）;

您可以使用在fxml文件中定義的fx：id和控制器中的註釋@FXML自動檢索treeView。

來源

2014-10-27 10:26:00 user2459733

但是，在這種情況下，TreeView的是NULL太 – earny1989 2014-10-28 00:23:02

你能不能把所有的來源嗎？ – user2459733 2014-10-28 07:54:31

完成了，現在一切都結束了 – earny1989 2014-10-28 14:20:17

JavaFX TreeView爲null爲什麼？

回答

相關問題