的JavaFX - 包裝FXML Java類控制器

Question

我有了一個TreeView控件FXML文件：

<AnchorPane id="AnchorPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="500.0" xmlns:fx="http://javafx.com/fxml" fx:controller="test.MyControllerClass"> 

<TreeView fx:id="locationTreeView" layoutX="12.0" layoutY="158.0" prefHeight="193.0" prefWidth="471.0" /> 

然後我的Java類控制器需要與此樹視圖來包裝，並添加TreeItem的動態。這就是問題所在，它不會加載這些TreeItem的。這是我的控制器下面的測試代碼：

public class MyControllerClass extends Application { 

    @FXML 
    private TreeView<String> locationTreeView; 

    @Override 
    public void start(Stage stage) throws Exception { 

     stage.initStyle(StageStyle.TRANSPARENT); 
     stage.getIcons().add(new Image(getClass().getResourceAsStream("myIcon.png"))); 

     Parent root = FXMLLoader.load(getClass().getResource("myInterface.fxml")); 

     Scene scene = new Scene(root); 
     stage.setScene(scene); 

     loadTreeItems(); 

     stage.show(); 
    } 

    // Just a simple example that still doesn't works 
    private void loadTreeItems() { 

     try { 
      TreeItem<String> root = new TreeItem<String>("Root Node"); 
      root.setExpanded(true); 
      root.getChildren().addAll(
       new TreeItem<String>("Item 1"), 
       new TreeItem<String>("Item 2"), 
       new TreeItem<String>("Item 3") 
      ); 

      locationTreeView = new TreeView<String>(root); 

     } catch (Exception exc) { 
      System.out.println("Error: " + exc.getMessage()); 
     } 
    } 

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

任何想法爲什麼它不工作？

Answer 1

有幾個原因使您的應用程序不工作：

1. 你需要使控制器和應用單獨的類。
2. 您應該允許FXML系統注入TreeView實例，而不是創建新實例（正如Aaron在他的答案中指出的那樣）。

你有你的應用程序目前的結構會發生什麼事情的方式是：

1. Java系統將創建MyControllerClass上啓動一個實例（並調用它的start方法）。
2. 的FXMLLoader將創建另一個實例的每個myInterface.fxml加載文件時MyControllerClass。
3. 的FXMLLoader將創建一個新的TreeView實例，並創建新MyControllerClass實例的locationTreeView成員執行了注射FXML。
4. FXMLLoader將嘗試在新的MyControllerClass（其中您沒有）上調用initialize方法。
5. 的FXMLLoader將不調用上新MyControllerClass的start方法。在
6. 你原來start方法調用原始的MyControllerClass將繼續處理並創建另一個新TreeView例如它會設置老MyControllerClass實例的locationTreeView成員。

---

我更新了你的代碼，使我上面提出的修改和現在的代碼工作。更新的code is available。

從正在運行的代碼的樣本屏幕截圖是：

MyApplicationClass.java

import javafx.animation.*; 
import javafx.application.Application; 
import javafx.event.*; 
import javafx.fxml.FXMLLoader; 
import javafx.scene.*; 
import javafx.scene.image.Image; 
import javafx.scene.input.MouseEvent; 
import javafx.stage.*; 
import javafx.util.Duration; 

/** Sample application to demonstrate programming an FXML interface. */ 
public class MyApplicationClass extends Application { 
    @Override public void start(final Stage stage) throws Exception { 
    // load the scene fxml UI. 
    // grabs the UI scenegraph view from the loader. 
    // grabs the UI controller for the view from the loader. 
    final FXMLLoader loader = new FXMLLoader(getClass().getResource("myInterface.fxml")); 
    final Parent root = (Parent) loader.load(); 
    final MyControllerClass controller = loader.<MyControllerClass>getController(); 

    // continuously refresh the TreeItems. 
    // demonstrates using controller methods to manipulate the controlled UI. 
    final Timeline timeline = new Timeline(
     new KeyFrame(
     Duration.seconds(3), 
     new TreeLoadingEventHandler(controller) 
    ) 
    ); 
    timeline.setCycleCount(Timeline.INDEFINITE); 
    timeline.play(); 

    // close the app if the user clicks on anywhere on the window. 
    // just provides a simple way to kill the demo app. 
    root.addEventFilter(MouseEvent.MOUSE_CLICKED, new EventHandler<MouseEvent>() { 
     @Override public void handle(MouseEvent t) { 
     stage.hide(); 
     } 
    }); 

    // initialize the stage. 
    stage.setScene(new Scene(root)); 
    stage.initStyle(StageStyle.TRANSPARENT); 
    stage.getIcons().add(new Image(getClass().getResourceAsStream("myIcon.png"))); 
    stage.show(); 
    } 

    /** small helper class for handling tree loading events. */ 
    private class TreeLoadingEventHandler implements EventHandler<ActionEvent> { 
    private MyControllerClass controller; 
    private int idx = 0; 

    TreeLoadingEventHandler(MyControllerClass controller) { 
     this.controller = controller; 
    } 

    @Override public void handle(ActionEvent t) { 
     controller.loadTreeItems("Loaded " + idx, "Loaded " + (idx + 1), "Loaded " + (idx + 2)); 
     idx += 3; 
    } 
    } 

    // main method is only for legacy support - java 8 won't call it for a javafx application. 
    public static void main(String[] args) { launch(args); } 
} 

MyControllerClass.java

import javafx.fxml.FXML; 
import javafx.scene.control.*; 

/** Sample controller class. */ 
public class MyControllerClass { 
    // the FXML annotation tells the loader to inject this variable before invoking initialize. 
    @FXML private TreeView<String> locationTreeView; 

    // the initialize method is automatically invoked by the FXMLLoader - it's magic 
    public void initialize() { 
    loadTreeItems("initial 1", "initial 2", "initial 3"); 
    } 

    // loads some strings into the tree in the application UI. 
    public void loadTreeItems(String... rootItems) { 
    TreeItem<String> root = new TreeItem<String>("Root Node"); 
    root.setExpanded(true); 
    for (String itemString: rootItems) { 
     root.getChildren().add(new TreeItem<String>(itemString)); 
    } 

    locationTreeView.setRoot(root); 
    } 
} 

myInterface.fxml

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

<?import javafx.scene.*?> 
<?import javafx.scene.control.*?> 
<?import javafx.scene.layout.*?> 

<AnchorPane id="AnchorPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" xmlns:fx="http://javafx.com/fxml" fx:controller="test.MyControllerClass"> 
    <TreeView fx:id="locationTreeView" layoutX="0" layoutY="0" prefHeight="193.0" prefWidth="471.0" /> 
</AnchorPane> 

Answer 2

在您的loadTreeItems（）函數中，您正在創建一個新的TreeView實例。這將替換FXML文件中定義的並使用不屬於場景圖的一部分的新實例附加到場景中的一個。

要將項目添加到通過FXMLLoader創建的TreeView中，您可以使用setRoot()函數。

private void loadTreeItems() { 

    try { 
     TreeItem<String> root = new TreeItem<String>("Root Node"); 
     root.setExpanded(true); 
     root.getChildren().addAll(
      new TreeItem<String>("Item 1"), 
      new TreeItem<String>("Item 2"), 
      new TreeItem<String>("Item 3") 
     ); 

     locationTreeView.setRoot(root); 

    } catch (Exception exc) { 
     System.out.println("Error: " + exc.getMessage()); 
    } 
}