I need to get to my stackpane that is nested inside a borberpane which is also nested in another borderpane(root).

I did not create this by code, I used scene-builder/FXML.

I am now trying to access it through code. The closes I got was by using a parent and got a unmodifiable list which seems to only have its two child but I cant seem to go deeper.

Here is the Hierarchy---

<BorderPane fx:id="rootPane" focusTraversable="true" minHeight="0.0" minWidth="0.0" prefHeight="771.0" prefWidth="1100.0" stylesheets="@styling.css" xmlns="http://javafx.com/javafx/18" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.passwordmanager2.HelloController">
   <center>
      <BorderPane fx:id="borderPane2" BorderPane.alignment="CENTER">
         <top>
            <StackPane fx:id="topBar" alignment="TOP_CENTER" focusTraversable="true" prefHeight="95.0" BorderPane.alignment="CENTER">
               <children>
                  .....

Here is main method

public class HelloApplication extends Application {


    @Override
    public void start(Stage stage) throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(HelloApplication.class.getResource("hello-view.fxml"));
        double width = 900.0;
        double height = 950.0;

        Scene scene = new Scene(fxmlLoader.load(), width, height);
        Parent root = fxmlLoader.getRoot();
        System.out.println(root.getChildrenUnmodifiable().get(3)); // trying to get stackPane

        stage.setScene(scene);
        stage.initStyle(StageStyle.UNDECORATED);

        ResizeHelper.addResizeListener(stage);

        stage.show();
    }

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

CodePudding user response：

You have to create fields named the same way you specified in the .fxml file (with fx:id="..."), for each component and use the @FXML annotation.

For example you have to add @FXML private BorderPane borderPane2; to access the border pane object.

The best way to implement that is using the MVC design pattern. References:

• 

  Project structure:

  src
   |
    - application (package)
        |
         -- Controller.java
        |
         -- Main.java
        |
         -- Test.fxml
        |
         -- application.css
  

  Main.java class:

  package application;
  
  import javafx.application.Application;
  import javafx.fxml.FXMLLoader;
  import javafx.scene.Scene;
  import javafx.scene.layout.AnchorPane;
  import javafx.stage.Stage;
  
  public class Main extends Application {
      @Override
      public void start(Stage stage) {
          
          try {
              FXMLLoader loader = new FXMLLoader(Main.class.getResource("Test.fxml"));
              AnchorPane basePane = (AnchorPane) loader.load();
              Scene scene = new Scene(basePane);
              scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
              stage.setTitle("Test");
              stage.setScene(scene);
              stage.show();
              
          } catch(Exception e) {
              e.printStackTrace();
          }
      }
      public static void main(String args[]) {
          launch(args);
      }
  }
  

  Controller.java class:

  package application;
  
  import javafx.event.ActionEvent;
  import javafx.fxml.FXML;
  import javafx.scene.control.Slider;
  import javafx.scene.control.TextField;
  import javafx.scene.control.Button;
  import javafx.scene.layout.AnchorPane;
  
  public class Controller {
      @FXML
      private AnchorPane base;
      @FXML private Slider sliderTest;
      @FXML private TextField textFieldTest;
      @FXML private Button buttonTest;
      
      private int counter = 0;
  
      public void initialize()
      {
          textFieldTest.setText(""   counter);
      }
      
      @FXML private void test(ActionEvent event)
      {
          counter  ;
          this.textFieldTest.setText(""   counter);
      }
  }
  

  Test.fxml file:

  <?xml version="1.0" encoding="UTF-8"?>
  
  <?import javafx.scene.control.Button?>
  <?import javafx.scene.control.Slider?>
  <?import javafx.scene.control.TextField?>
  <?import javafx.scene.layout.AnchorPane?>
  
  <AnchorPane id="base" fx:id="base" prefHeight="400.0" prefWidth="400.0" xmlns="http://javafx.com/javafx/18" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.Controller">
     <children>
        <TextField fx:id="textFieldTest" layoutX="125.0" layoutY="187.0" />
        <Button fx:id="buttonTest" layoutX="174.0" layoutY="273.0" mnemonicParsing="false" onAction="#test" text="Increment" />
        <Slider fx:id="sliderTest" layoutX="14.0" layoutY="33.0" />
     </children>
  </AnchorPane>
  

  application.css file:

  .slider {
      -fx-base: red;
  }
  .button {
      -fx-base: blue;
  }
  

  Another way to access a component (for example if it doesn't have a fx:id), you could start from the parent and, knowing the child node index, or iterating through them, you could get the interested node and cast it.
  Example:

  Node n = base.getChildren().get(0);
  TextField tf = (TextField) n;
  System.out.println(tf);
  tf.setText("Hello JavaFX");
  

  Output:

  TextField[id=textFieldTest, styleClass=text-input text-field]
  

  here the TextField is the 1st child of AnchorPane: