Dfyjkt

Okay, I re-edited this question with a much easier smaller example.

My question is though, I have a StackPane, myStackPane that I am trying to load the Label onto. When the program first runs, the StackPane is empty. When I click on the handleButtonAction button it takes me to another stage so I can enter in the text I want on the label. When that new text is saved, it passes the new settings back to the main controller and updates the text of the label. It then adds the label to the StackPane.

However.... It's not displaying the new label in the stackpane. I know I am getting into the method and the variable is being passed correctly since I can System.out.println everything and it's all appropriate. But why will it not add it to the StackPane?

Thanks everyone!

Problems.java

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class Problems extends Application 

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

 Scene scene = new Scene(root);

 stage.setScene(scene);
 stage.show();
 

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

FXMLDocumentController

import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class FXMLDocumentController implements Initializable 

 @FXML
 private Button button;
 @FXML
 private StackPane myStackPane;

 private Label label = new Label("Text 1");

 @FXML
 private void handleButtonAction(ActionEvent event) 
 FXMLLoader secondLoader = new FXMLLoader();

 secondLoader.setLocation(getClass().getResource("FXMLSecond.fxml"));

 try 
 secondLoader.load();
 catch (IOException e) 
 

 FXMLSecondController secondController = secondLoader.getController();

 secondController.setFieldText(label.getText());

 Parent p = secondLoader.getRoot();
 Stage stage = new Stage();
 stage.setScene(new Scene(p));
 stage.showAndWait();
 

 public void putLabelOnStackPane(String value) 
 label.setText(value);

 myStackPane.getChildren().add(label);
 

 @Override
 public void initialize(URL url, ResourceBundle rb) 
 // TODO
 

FXMLSecondController

import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.stage.Stage;

public class FXMLSecondController implements Initializable 

 @FXML
 private Button saveText;
 @FXML
 private TextField textField;

 /**
 * Initializes the controller class.
 */


 @Override
 public void initialize(URL url, ResourceBundle rb) 
 // TODO
 

 @FXML
 private void saveTextBtnPressed(ActionEvent event) 
 FXMLLoader firstLoader = new FXMLLoader();

 firstLoader.setLocation(getClass().getResource("FXMLDocument.fxml"));

 try 
 firstLoader.load();
 catch (IOException e) 
 

 FXMLDocumentController firstController = firstLoader.getController();

 firstController.putLabelOnStackPane(textField.getText());

 Stage stage = (Stage) saveText.getScene().getWindow();
 stage.close();
 

 public void setFieldText(String value) 
 textField.setText(value);
 

FXMLDocument

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.StackPane?>

<AnchorPane id="AnchorPane" prefHeight="200" prefWidth="320" xmlns="http://javafx.com/javafx/10.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="problems.FXMLDocumentController">
 <children>
 <Button fx:id="button" layoutX="128.0" layoutY="14.0" onAction="#handleButtonAction" text="Click Me!" />
 <StackPane fx:id="myStackPane" layoutX="61.0" layoutY="45.0" prefHeight="150.0" prefWidth="200.0" />
 </children>
</AnchorPane>

FXMLSecond

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>


<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/10.0.1" fx:controller="problems.FXMLSecondController">
 <children>
 <Button fx:id="saveText" layoutX="274.0" layoutY="106.0" mnemonicParsing="false" onAction="#saveTextBtnPressed" text="Button" />
 <TextField fx:id="textField" layoutX="226.0" layoutY="175.0" />
 </children>
</AnchorPane>

The main issue is that by

FXMLLoader firstLoader = new FXMLLoader();
firstLoader.setLocation(getClass().getResource("FXMLDocument.fxml"));

you actually construct a new FXMLLoader rather then getting a reference to the open one.

You could get a reference to the open FXMLLoader by, for example, using static members (see here) but it would be better to use a slightly different approach:

FXMLDocumentController.java

public class FXMLDocumentController implements Initializable 

 @FXML
 private Button button;
 @FXML
 private StackPane myStackPane;

 private Label label = new Label("Text 1");

 @FXML
 private void handleButtonAction(ActionEvent event) 

 FXMLLoader secondLoader = new FXMLLoader();
 secondLoader.setLocation(getClass().getResource("FXMLSecond.fxml"));

 try 
 secondLoader.load();
 catch (IOException e) e.printStackTrace(); 

 FXMLSecondController secondController = secondLoader.getController();
 //secondController.setFieldText(label.getText());
 secondController.setTextProperty(label.textProperty());

 Parent p = secondLoader.getRoot();
 Stage stage = new Stage();
 stage.setScene(new Scene(p));
 stage.showAndWait();
 myStackPane.getChildren().add(label);
 

 /*
 public void putLabelOnStackPane(String value) 
 label.setText(value);

 myStackPane.getChildren().add(label);
 */

 @Override
 public void initialize(URL url, ResourceBundle rb) //no need to implement Initializable 
 //if initialize not used 
 

FXMLSecondController.java

public class FXMLSecondController implements Initializable 

 @FXML
 private Button saveText;
 @FXML
 private TextField textField;

 private StringProperty labelStringProperty;

 @Override
 public void initialize(URL url, ResourceBundle rb) 
 textField.setEditable(true);
 

 @FXML
 private void saveTextBtnPressed(ActionEvent event) 

 /** By doing so you actually construct a new FXMLDocument
 FXMLLoader firstLoader = new FXMLLoader();
 firstLoader.setLocation(getClass().getResource("FXMLDocument.fxml"));

 try 
 firstLoader.load();
 catch (IOException e) 
 

 FXMLDocumentController firstController = firstLoader.getController();
 firstController.putLabelOnStackPane(textField.getText());
 */
 labelStringProperty.set(textField.getText());
 Stage stage = (Stage) saveText.getScene().getWindow();
 stage.close();
 

 /*
 public void setFieldText(String value) 
 textField.setText(value);
 */

 public void setTextProperty(StringProperty labelStringProperty) 
 this.labelStringProperty = labelStringProperty;
 textField.setText(labelStringProperty.get());
 

Also consider using Dialog for input.

EDIT
To have FXMLSecondController add a label to FXMLDocoment change FXMLDocumentController to pass the needed references to FXMLSecondController:

public class FXMLDocumentController 

 @FXML
 private Button button;
 @FXML
 private StackPane myStackPane;

 private Label label = new Label("Text 1");

 @FXML
 private void handleButtonAction(ActionEvent event) 

 FXMLLoader secondLoader = new FXMLLoader();
 secondLoader.setLocation(getClass().getResource("FXMLSecond.fxml"));

 try 
 secondLoader.load();
 catch (IOException e) e.printStackTrace(); 

 FXMLSecondController secondController = secondLoader.getController();
 secondController.setRefrences(myStackPane.getChildren(), label);

 Parent p = secondLoader.getRoot();
 Stage stage = new Stage();
 stage.setScene(new Scene(p));
 stage.showAndWait();
 

And have FXMLSecondController use those references:

public class FXMLSecondController 

 @FXML
 private Button saveText;
 @FXML
 private TextField textField;

 private ObservableList<Node> children;
 private Label label;

 @FXML
 private void saveTextBtnPressed(ActionEvent event) 

 label.setText(textField.getText());
 children.add(label);
 Stage stage = (Stage) saveText.getScene().getWindow();
 stage.close();
 

 public void setRefrences(ObservableList<Node> children, Label label) 
 this.children = children;
 this.label = label;
 textField.setText(label.getText());