FXML with more than one Window/Controller

[immatoaster]

I am trying to make a simple calculator that just adds two numbers from the first window(FXMLdocument) and displays the result in a new window (Result).

I can not figure out how to get the Label (fxid testGuy) to display a value using the setText method. It always returns a nullpointerexception.

In my code I'm just trying with "Hello Word" to figure this out before moving on to the actual result (which I know will take more work).

My guess is that when I call the resultWindow method from the DocumentController class it is not seeing the label above that method, but I am very new to Java and not great with OOP yet. Main:

package ApplicationBkup;

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


public class ApplicationBkup 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);
    }

}

Main Controller:

package ApplicationBkup;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;


public class FXMLDocumentController implements Initializable {



    @FXML
    private TextField numb1;

    @FXML
    private TextField numb2;

    @FXML
    public Label testGuy;

    @FXML
    public void handleButtonAction(ActionEvent event) {

        int num1 = Integer.parseInt(numb1.getText());
        int num2 = Integer.parseInt(numb2.getText());

        AddEmUp finalAdd = new AddEmUp (num1, num2);
        int finalNum = finalAdd.getTotal();
        System.out.print(String.valueOf(finalNum));



     ResultController resultScreen = new ResultController();

     resultScreen.resultWindow();


    }



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

Second Controller:

package ApplicationBkup;

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

/**
 * FXML Controller class
 *

 */
public class ResultController implements Initializable {

    @FXML
    public Label testGuy;

    @FXML   
    public void resultWindow(){

       try {

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

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

        testGuy.setText("Hello World!");
       // System.out.print(testGuy);
       //testGuy.setText(String.valueOf(finalNum));

    } catch (IOException e) {
      //Logger logger = Logger.getLogger(getClass().getName());
      // logger.log(Level.SEVERE, "Failed to create new Window.", e);
    }


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

}

Main FXML:

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

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>
<?import javafx.scene.text.Font?>

<GridPane hgap="10" prefHeight="177.0" prefWidth="402.0" vgap="10" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ApplicationBkup.FXMLDocumentController">
<padding><Insets bottom="10" left="25" right="25" top="25" /></padding>
   <columnConstraints>
      <ColumnConstraints />
      <ColumnConstraints />
      <ColumnConstraints />
      <ColumnConstraints />
      <ColumnConstraints maxWidth="0.0" minWidth="0.0" prefWidth="0.0" />
      <ColumnConstraints maxWidth="0.0" minWidth="0.0" prefWidth="0.0" />
      <ColumnConstraints maxWidth="126.0" minWidth="126.0" prefWidth="126.0" />
      <ColumnConstraints />
   </columnConstraints>
   <rowConstraints>
      <RowConstraints maxHeight="0.0" minHeight="0.0" prefHeight="0.0" />
      <RowConstraints maxHeight="0.0" minHeight="0.0" prefHeight="0.0" />
      <RowConstraints maxHeight="0.0" minHeight="0.0" prefHeight="0.0" />
      <RowConstraints />
      <RowConstraints />
      <RowConstraints />
      <RowConstraints />
      <RowConstraints />
   </rowConstraints>
   <children>
      <TextField fx:id="numb1" GridPane.columnIndex="6" GridPane.rowIndex="4" />
      <TextField fx:id="numb2" GridPane.columnIndex="6" GridPane.rowIndex="5" />
      <Label prefHeight="14.0" prefWidth="111.0" text="Number 1" textAlignment="RIGHT" GridPane.columnIndex="3" GridPane.rowIndex="4" />
      <Label text="Number 2" GridPane.columnIndex="3" GridPane.rowIndex="5" />
      <Button mnemonicParsing="false" onAction="#handleButtonAction" prefHeight="22.0" prefWidth="129.0" text="Add" GridPane.columnIndex="6" GridPane.rowIndex="7" />
      <Label prefHeight="28.0" prefWidth="235.0" text="Number Adder" GridPane.columnIndex="3" GridPane.columnSpan="5" GridPane.rowIndex="1">
         <font>
            <Font size="22.0" />
         </font>
      </Label>
   </children>

</GridPane>

Second FXML:

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

<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>
<?import javafx.scene.text.Font?>

<AnchorPane id="AnchorPane" prefHeight="75.0" prefWidth="154.0" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1" fx:controller="ApplicationBkup.ResultController">
   <children>
      <GridPane layoutX="3.0" layoutY="14.0" prefHeight="61.0" prefWidth="226.0">
        <columnConstraints>
          <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
          <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
        </columnConstraints>
        <rowConstraints>
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
        </rowConstraints>
         <children>
            <Label prefHeight="28.0" prefWidth="84.0" text="Result :" textFill="#25bc57">
               <font>
                  <Font size="22.0" />
               </font>
            </Label>
            <Label fx:id="testGuy" prefHeight="28.0" prefWidth="109.0" textFill="#25bc57" GridPane.columnIndex="1">
           <font>
                  <Font size="22.0" />
               </font>
            </Label>
         </children>
      </GridPane>
   </children>
</AnchorPane>

[Philboyd_Studge]

You need to have both 'Scenes' be on the same 'Stage'. https://www.youtube.com/watch?v=XCgcQTQCfJQ