Java FX cannot setLabel when after changing scenes

Question

Main class

package application;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;


/*
Parent root = FXMLLoader.load(getClass().getResource("graphicorg.fxml"));

Scene scene = new Scene(root);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());



primaryStage.setScene(scene);
primaryStage.show();
**/



public class Main extends Application {
    Button S1Butt;
    @Override
    public void start(Stage primaryStage) {
        try {
            Parent root = FXMLLoader.load(getClass().getResource("graphicorg.fxml"));

            Scene scene = new Scene(root);
            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());



            primaryStage.setScene(scene);
            primaryStage.show();
            
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
    
    public static void main(String[] args) {
        launch(args);
    }
}

Controller that changes through 3 scenes that are circularly connected until the person decides to end the program with scene 3

package application;
import java.io.IOException;
import javafx.application.Platform;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.stage.Stage;

public class SceneController {

    private Stage stage;
    private Scene scene;
    private Parent root;

    
@FXML   
private TextField BetField;
@FXML
private Label bal;


public void S1(ActionEvent event) throws IOException {
    this.bal.setText("Test Text");
    System.out.println(bal);
        root = FXMLLoader.load(getClass().getResource("graphicorg.fxml"));
        
        stage  = (Stage)(((Node)event.getSource()).getScene().getWindow());
        
        scene = new Scene(root);
        stage.setScene(scene);
        stage.show();
    }
public void S2(ActionEvent event) throws IOException {

    //System.out.println(bal);
    //this.bal.setText("Test Text");

    String test = BetField.getText();

    
    root = FXMLLoader.load(getClass().getResource("Scene2.fxml"));
    
    stage  = (Stage)(((Node)event.getSource()).getScene().getWindow());
    scene = new Scene(root);
    stage.setScene(scene);
    stage.show();
        
    }
public void S3(ActionEvent event) throws IOException {
    
    root = FXMLLoader.load(getClass().getResource("Scene3.fxml"));
    stage  = (Stage)(((Node)event.getSource()).getScene().getWindow());
    scene = new Scene(root);
    stage.setScene(scene);
    stage.show();
    
    
}

public void exit(ActionEvent event) {
    Platform.exit();
}


    
}

FXML for the 1st scene

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Font?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/17" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.SceneController">
   <children>
      <HBox layoutX="43.0" layoutY="43.0" prefHeight="141.0" prefWidth="520.0">
         <children>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@card%20back%20blue.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@card%20back%20red.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@card%20back%20blue.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@card%20back%20red.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@card%20back%20blue.png" />
               </image>
            </ImageView>
         </children>
      </HBox>
      <ImageView fitHeight="150.0" fitWidth="200.0" layoutX="43.0" layoutY="215.0" pickOnBounds="true" preserveRatio="true">
         <image>
            <Image url="@download%20(1).jpeg" />
         </image>
      </ImageView>
      <VBox layoutX="331.0" layoutY="234.0" prefHeight="157.0" prefWidth="105.0">
         <children>
            <Label fx:id="bal" prefHeight="41.0" prefWidth="80.0" text="Player Balance:">
               <font>
                  <Font name="Impact" size="12.0" />
               </font>
            </Label>
            <TextField fx:id="BetField" onAction="#S2" prefHeight="7.0" prefWidth="100.0" promptText="Enter Bet" text="Enter Bet" />
            <Button mnemonicParsing="false" onAction="#S2" text="Enter" />
         </children>
      </VBox>
   </children>
</AnchorPane>

Scene 2 FXML

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Font?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/17" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.SceneController">
   <children>
      <HBox layoutX="43.0" layoutY="43.0" prefHeight="141.0" prefWidth="520.0">
         <children>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/7_of_spades.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/4_of_diamonds.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/3_of_spades.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/2_of_clubs.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/4_of_diamonds.png" />
               </image>
            </ImageView>
         </children>
      </HBox>
      <ImageView fitHeight="150.0" fitWidth="200.0" layoutX="43.0" layoutY="215.0" pickOnBounds="true" preserveRatio="true">
         <image>
            <Image url="@Cards/download%20(1).jpeg" />
         </image>
      </ImageView>
      <VBox layoutX="239.0" layoutY="268.0" prefHeight="122.0" prefWidth="259.0">
         <children>
            <Label prefHeight="50.0" prefWidth="206.0" text="Click the cards that you would like to keep">
               <font>
                  <Font name="Impact" size="12.0" />
               </font>
            </Label>
            <Button mnemonicParsing="false" onAction="#S3" text="Next" />
         </children>
      </VBox>
   </children>
</AnchorPane>

Scene 3 FXML

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.Separator?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Font?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/17" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.SceneController">
   <children>
      <HBox layoutX="43.0" layoutY="43.0" prefHeight="141.0" prefWidth="520.0">
         <children>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/7_of_spades.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/4_of_diamonds.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/3_of_spades.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/2_of_clubs.png" />
               </image>
            </ImageView>
            <ImageView fitHeight="150.0" fitWidth="200.0" pickOnBounds="true" preserveRatio="true">
               <image>
                  <Image url="@Cards/4_of_diamonds.png" />
               </image>
            </ImageView>
         </children>
      </HBox>
      <ImageView fitHeight="150.0" fitWidth="200.0" layoutX="43.0" layoutY="215.0" pickOnBounds="true" preserveRatio="true">
         <image>
            <Image url="@download%20(1).jpeg" />
         </image>
      </ImageView>
      <VBox layoutX="239.0" layoutY="268.0" prefHeight="122.0" prefWidth="259.0">
         <children>
            <Label text="Royal Flush">
               <font>
                  <Font name="Impact" size="12.0" />
               </font>
            </Label>
            <Label prefHeight="50.0" prefWidth="206.0" text="Play Again">
               <font>
                  <Font name="Impact" size="12.0" />
               </font>
            </Label>
            <HBox prefHeight="100.0" prefWidth="200.0">
               <children>
                  <Button mnemonicParsing="false" onAction="#S1" prefHeight="26.0" prefWidth="118.0" text="Yes" />
                  <Separator opacity="0.0" prefHeight="8.0" prefWidth="59.0" />
                  <Button mnemonicParsing="false" onAction="#exit" prefHeight="26.0" prefWidth="122.0" text="No" />
               </children>
            </HBox>
         </children>
      </VBox>
   </children>
</AnchorPane>

This is the error message:

Caused by: java.lang.NullPointerException: Cannot invoke "javafx.scene.control.Label.setText(String)" because "this.bal" is null at application.SceneController.S1(SceneController.java:32)

why is it null?

If I use this.bal.setText("Test Text"); in the S2 method from the controller it works however when the first scene is reloaded upon pressing the yes button button in Scene 3 FXML it is set back to the default value "Player Balance:" and not "Test Text".

How can I fix it so that the Text value of bal is permanently set to Test Text instead of having it reset?

Thank You

for your next question: [mcve] please (mind the __M__!, and include the complete stacktrace formatted as code) and stick to java naming conventions — kleopatra, Dec 21 '21 at 05:56
*"why is it null?"*. The method `s1(...)` is called on the controller that is created when `Scene3.fxml` is loaded. There is no element in `Scene3.fxml` with `fx:id="bal"`, so `bal` is null in that controller. — James_D, Dec 21 '21 at 15:20

Java FX cannot setLabel when after changing scenes

0 Answers0