javaFX-如何从另一个控制器中使用控制器的函数或对象

Question

我有一个简单的主：

MainClassFXGUI.java

public class MainClassFXGui extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("MyProgramMainGuiTab.fxml"));

        Scene scene = new Scene(root);
        stage.setScene(scene);
        stage.setTitle("Assicurazione");
        stage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }
}

和三个fxml文件,其中一个包含其他两个文件

<fx:include source="MyTab1.fxml" />

...
<TabPane maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" prefHeight="5000.0" prefWidth="5000.0" tabClosingPolicy="UNAVAILABLE">
          <tabs>
              <Tab closable="false" text="MyTab1">
                   <content>
    <fx:include source="MyTab1.fxml" />
                   </content>
              </Tab>
              <Tab closable="false" text="MyTab2">
                   <content>
    <fx:include source="MyTab2.fxml" />
                   </content>
              </Tab>
          </tabs>
    </TabPane>
...

....
@FXML
private Label LeftSt;
/**
 * Initializes the controller class.
 */
@Override
public void initialize(URL url, ResourceBundle rb) {
    LeftSt.setText("");
}    

public void setLeftSt(String st){
    LeftSt.setText(st);
}
...

@FXML
private void handleButtonAction(ActionEvent event) {
    System.out.println("You clicked me!");
    setLeftSt("Can I change the label of the MyProgramMainGuiTabController?");
}

private MyProgramMainGuiTabController controller;

@FXML
private void handleButtonAction(ActionEvent event) {
        System.out.println("You clicked me!");
        controller.setLeftSt("Can I change the label of the MyProgramMainGuiTabController?");
}

@Override
public void initialize(URL url, ResourceBundle rb) {
    FXMLLoader fxmlLoader = new
    FXMLLoader(getClass().getResource("MyProgramMainGuiTab.fxml"));
    try {
         fxmlLoader.load();            
    } catch (IOException exception) {
         throw new RuntimeException(exception);
    }
    controller = (MyProgramMainGuiTabController)fxmlLoader.getController();
}

但是我有一个空指针异常，或者如果我移动handleButtonAction函数中对象'controller'实例化的代码，我没有任何错误，但是标签没有改变。

也许我可以在MainClassFXGUI.java中创建一个静态场景和一个静态阶段？但我不知道我该怎么用它们...

MainClassFXGUI.java

public class MainClassFXGui extends Application {
    static private Scene scene;
    static private Stage stage;

    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("MyProgramMainGuiTab.fxml"));

        this.scene = new Scene(root);
        stage.setScene(scene);
        stage.setTitle("Assicurazione");
        stage.show();
        this.stage = stage;
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

    public static Scene getScene(){
        return AssicurazioneFXGui.scene;
    }

    public static Stage getStage(){
        return AssicurazioneFXGui.stage;
    }

}

Answer 1

在MyTab1Controller中定义StringProperty，使用通常的方法：

public class MyTab1Controller {

    private final StringProperty leftSt = new SimpleStringProperty();

    public StringProperty leftStProperty() { 
        return leftSt ;
    }

    public final String getLeftSt() {
        return leftStProperty().get();
    }

    public final void setLeftSt(String leftSt) {
        leftStProperty().set(leftSt);
    }

    // ...

    @FXML
    public void handleButtonAction() {
        setLeftSt(...);
    }

    // ...
}

现在将fx:id属性分配给fx:include标记：

<Tab closable="false" text="MyTab1">
    <content>
        <fx:include fx:id="myTab1" source="MyTab1.fxml" />
    </content>
</Tab>

这意味着您可以将MyTab1.FXML的控制器注入到包含它的FXML的控制器(MyProgrammaInguitabController):

public class MyProgramMainGuiTabController {

    @FXML
    private MyTab1Controller myTab1Controller ;

}

public class MyProgramMainGuiTabController {

    @FXML
    private MyTab1Controller myTab1Controller ;

    @FXML
    private Label leftSt;

    public void initialize() {
        leftSt.setText("");
        myTab1Controller.leftStProperty().addListener((obs, oldValue, newValue) -> 
            leftSt.setText(newValue));
    }    
}