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JavaFX/FXML: TableView correctly refreshing in case of editing items, but not in case of removing items (ArrayList->TableView)

I'm working on a larger project (together with quite a number of fellow students), and I'm trying to display an arrayList (which type we're using over and over again in our project, so I wouldn't love to change all these to ObservableLists just for my rather small issue) in a TableView.
I've created a smaller project just in order to get to the heart of the problem and to show you:
In the class editMyGrades (together with an fxml file of the same name) I want to display my SUBJECTs (-> String subjectName), each one with its GRADE (-> int grade) in a TableView.
Initializing the parent root and the tableView the ArrayList subjects is transformed to an ObservableList, which is loaded into the TableView.
I really would like to understand theoretically, why changing GRADEs works with the tableView, but removing doesn't, and to know what to do about it practically ;-)
Thank you very much in advance!
Main class:
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import java.util.ArrayList;
public class Main extends Application {
private static ArrayList<Subject> subjects = new ArrayList<>();
public static ArrayList<Subject> getSubjects () {return subjects;}
// private static ObservableList<Subject> subjects = FXCollections.observableArrayList();
// public static ObservableList<Subject> getSubjects () {return subjects;}
public static void main (String[] args) {
subjects.add(new Subject("computer science", 2));
subjects.add(new Subject("literature", 4));
launch (args);
}
public void start (Stage primaryStage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("/editMyGrades.fxml"));
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.show();
}
}
Class Subject:
public class Subject {
private String subjectName;
private int grade;
public Subject (String subjectName, int grade) {
this.subjectName = subjectName;
this.grade = grade;
}
public String getSubjectName () {return subjectName;}
public int getGrade () {return grade;}
public void setGrade (int grade) {this.grade = grade;}
}
controlling class editMyGrades:
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.input.MouseEvent;
import java.util.ArrayList;
public class editMyGrades {
Subject subjectToEdit;
#FXML
private TableView<Subject> tableView;
#FXML
private TableColumn<Subject, String> subjectCol;
#FXML
private TableColumn<Subject, Number> gradeCol;
#FXML
private TextField textField;
#FXML
private Button changeButton;
#FXML
private Button deleteButton;
#FXML
public void initialize() {
subjectCol.setCellValueFactory(new PropertyValueFactory<>("subjectName"));
gradeCol.setCellValueFactory(new PropertyValueFactory<>("grade"));
//tableView.setItems (FXCollections.observableArrayList(Main.getSubjects()));
ObservableList<Subject> subjects = FXCollections.observableArrayList(Main.getSubjects());
tableView.setItems(subjects);
}
#FXML
private void tableViewClicked(MouseEvent event) {
if (event.getClickCount() == 2) {
subjectToEdit = tableView.getSelectionModel().getSelectedItem();
textField.setText ("" + tableView.getSelectionModel().getSelectedItem().getGrade());
}
}
#FXML
private void change(ActionEvent event) {
subjectToEdit.setGrade(Integer.parseInt(textField.getText()));
textField.clear();
tableView.refresh();
}
#FXML
private void delete (ActionEvent event) {
Subject selectedSubject = tableView.getSelectionModel().getSelectedItem();
ArrayList<Subject> subjects = Main.getSubjects();
subjects.remove(selectedSubject);
tableView.refresh();
}
}
editingMyGrades.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="editMyGrades">
<children>
<Label text="change your grades!" />
<HBox>
<children>
<TableView fx:id="tableView" onMouseClicked="#tableViewClicked" prefHeight="200.0" prefWidth="518.0">
<columns>
<TableColumn fx:id="subjectCol" prefWidth="262.0" text="subject" />
<TableColumn fx:id="gradeCol" minWidth="0.0" prefWidth="146.0" text="grade" />
</columns>
</TableView>
<VBox alignment="CENTER">
<children>
<Button mnemonicParsing="false" onAction="#delete" text="deleteButton" />
</children>
</VBox>
</children>
</HBox>
<TextField fx:id="textField" maxWidth="100.0" />
<Button fx:id="changeButton" mnemonicParsing="false" onAction="#change" text="Change!" />
</children>
</VBox>

When working with JavaFX it's good practice to always use FXCollections.
When you make a modification to the ArrayList, the changes are not generating list change nofications. You must get the ObservableList from the tableview and perform the operations on it since it is the wrapper (the smart list) that is backed by your ArrayList.

Thank you indeed for your explanations! In fact in my real problem I'm using MVC, but the Controller object is located in the main - static -, and as it appears, it can't be done in other way. For the illustration of my problem I thought id wouldn't make a difference, if I had a static controller object with the list or just the list itself (perhaps I was wrong ...).
Now, having tried to apply everything you told me, it's just the other way around: the tableView displays removements, but no changes.
just the fxml control class EditMyGrades:
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.input.MouseEvent;
public class EditMyGrades {
private ObservableList<Subject> subjects = FXCollections.observableArrayList();
private Subject subjectToEdit;
#FXML
private TableView<Subject> tableView;
#FXML
private TableColumn<Subject, String> subjectCol;
#FXML
private TableColumn<Subject, Number> gradeCol;
#FXML
private TextField textField;
#FXML
private Button changeButton;
#FXML
private Button deleteButton;
#FXML
public void initialize() {
subjectCol.setCellValueFactory(new PropertyValueFactory<>("subjectName"));
gradeCol.setCellValueFactory(new PropertyValueFactory<>("grade"));
subjects.add(new Subject("computer science", 2));
subjects.add(new Subject("literature", 4));
tableView.setItems(subjects);
}
#FXML
private void tableViewClicked(MouseEvent event) {
if (event.getClickCount() == 2) {
subjectToEdit = tableView.getSelectionModel().getSelectedItem();
textField.setText ("" + tableView.getSelectionModel().getSelectedItem().getGrade());
}
}
#FXML
private void change(ActionEvent event) {
subjectToEdit.setGrade(Integer.parseInt(textField.getText()));
textField.clear();
}
#FXML
private void delete (ActionEvent event) {
ObservableList<Subject> subjects = tableView.getItems();
Subject selectedSubject = tableView.getSelectionModel().getSelectedItem();
subjects.remove(selectedSubject);
}
}

NullPointerException Setting ComboBox From FXML [duplicate]

I'm really struggling to understand JavaFX controllers, my aim is to write to a TextArea to act as a log.
My code is below, but I want to be able to change values ETC from another class that I can call when needed. I have tried to create a controller class that extents Initializable but i cant get it to work. Could some one steer me in the correct direction?
I want to move the #FXML code at the bottom to another class and it update the Scene.
package application;
import javafx.event.ActionEvent;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import java.io.IOException;
import javafx.application.Application;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;
public class Main extends Application {
#Override
public void start(Stage primaryStage) {
try {
Parent root = FXMLLoader.load(getClass().getResource("Root.fxml"));
Scene scene = new Scene(root,504,325);
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);
}
public Thread thread = new Thread(new webimporter());
#FXML
public Label runningLabel;
#FXML
public TextArea txtArea;
#FXML
void runClick(ActionEvent event) throws IOException{
changeLabelValue("Importer running...");
thread.start();
}
#FXML
protected void stopClick(ActionEvent event){
changeLabelValue("Importer stopped...");
thread.interrupt();
}
#FXML
void changeLabelValue(String newText){
runningLabel.setText(newText);
}
void changeTextAreaValue(String newText1){
txtArea.setText(newText1);
}
}

Don't make the Application class a controller. It's a sin. There are other questions and answers which address this, but my search skills cannot find them at this time.
The reason it is a sin is:
You are only supposed to have one Application instance, and, by default, the loader will make a new instance, so you end up with two application objects.
Referencing the member objects is confusing, because the original launched application doesn't have the #FXML injected fields, but the loader created application instance does have #FXML inject fields.
Also, unrelated advice: Don't start trying to write multi-threaded code until you have the application at least working to the extent where it displays your UI.
A multi-threaded logger for JavaFX is in the answer to Most efficient way to log messages to JavaFX TextArea via threads with simple custom logging frameworks, though unfortunately it is not straight-forward in its implementation and comes with little documentation.
textlogger/Root.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefWidth="400.0" spacing="10.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="textlogger.ImportController">
<children>
<HBox alignment="BASELINE_LEFT" minHeight="-Infinity" minWidth="-Infinity" spacing="10.0">
<children>
<Button mnemonicParsing="false" onAction="#run" text="Run" />
<Button mnemonicParsing="false" onAction="#stop" text="Stop" />
<Label fx:id="runningLabel" />
</children>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
</HBox>
<TextArea fx:id="textArea" editable="false" prefHeight="200.0" prefWidth="200.0" />
</children>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
</VBox>
textlogger.ImportController.java
package textlogger;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import java.io.IOException;
public class ImportController {
#FXML
private Label runningLabel;
#FXML
private TextArea textArea;
private WebImporter importer;
#FXML
void run(ActionEvent event) throws IOException {
changeLabelValue("Importer running...");
if (importer == null) {
importer = new WebImporter(textArea);
Thread thread = new Thread(
importer
);
thread.setDaemon(true);
thread.start();
}
}
#FXML
void stop(ActionEvent event){
changeLabelValue("Importer stopped...");
if (importer != null) {
importer.cancel();
importer = null;
}
}
private void changeLabelValue(String newText){
runningLabel.setText(newText);
}
}
textlogger.WebImporter.java
import javafx.application.Platform;
import javafx.concurrent.Task;
import javafx.scene.control.TextArea;
import java.time.LocalTime;
public class WebImporter extends Task<Void> {
private final TextArea textArea;
public WebImporter(TextArea textArea) {
this.textArea = textArea;
}
#Override
protected Void call() throws Exception {
try {
while (!isCancelled()) {
Thread.sleep(500);
Platform.runLater(
() -> textArea.setText(
textArea.getText() + LocalTime.now() + "\n"
)
);
}
} catch (InterruptedException e) {
Thread.interrupted();
}
return null;
}
}
textlogger.TextLoggingSample.java
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class TextLoggingSample extends Application {
#Override
public void start(Stage stage) {
try {
FXMLLoader loader = new FXMLLoader();
Parent root = loader.load(
getClass().getResourceAsStream(
"Root.fxml"
)
);
Scene scene = new Scene(root);
stage.setScene(scene);
stage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}

cant change label and buttons values

I'm writing a simple quiz-game application using JavaFx. I want set text on label and buttons with data from a list and table.
I created three class: Main, Controller and Quiz.fxml. I have problem with communication classes and method.
In 'Main.java' I created object "Controller controller = new Controller()" and I call method "controller.setText" from 'Controller.java' class.
Now, I have a few options:
-if declate list(ArrayList questions) and tab(String[][] answers) in constuctor 'public Controller(){}' app doesnt work, I get error in this line " "
-if declare everything in 'Text()' method(list, tab and setting text on label) application run but values buttons and label are not changed
-if I declare list and tab in 'setData()', and next I want to change the buttons and label value from 'Text()' method, I cant see the list and I have to declare the same list 'questions' in 'Text()'
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
try {
Parent root = FXMLLoader.load(getClass().getResource("/Controller/Quiz.fxml"));
Scene scene = new Scene(root,500,400)
primaryStage.setScene(scene);
primaryStage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
Controller controller = new Controller();
controller.Text();}
Controller class:
public class Controller {
#FXML private Label questionLabel;
#FXML private RadioButton answer_btn1;
#FXML private RadioButton answer_btn2;
#FXML private RadioButton answer_btn3;
#FXML private RadioButton answer_btn4;
#FXML private Button nextBtn;
public void Text() {
List <String> questions = new ArrayList<String>();
questions.add("pytanie1");
questions.add("pytanie2");
questions.add("pytanie3");
questions.add("pytanie4");
questions.add("pytanie5");
questions.add("pytanie6");
questions.add("pytanie7");
questions.add("pytanie8");
questions.add("pytanie9");
questions.add("pytanie10");
String[][] answers = new String[1][4];
answers[1][1] = "a) odp";
answers[1][2] = "b) odp";
answers[1][3] = "c) odp";
answers[1][4] = "d) odp";
questionLabel.setText("");
questionLabel.setText(questionLabel.getText()+answers[1][1]);
answer_btn1.setText("aaa");
}
What do I have to do to change name buttons and label?

You have a couple problems with your code.
Array index starts at zero and if necessary should end at arrayLength - 1. Your code: answers[1][1] = "a) odp"; ... answers[1][4] = "d) odp";. What it should be: answers[0][0] = "a) odp"; ... answers[0][3] = "d) odp";
Initialzing the Controller should be done in the Controller's initialize method.
The sample code below:
Main:
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
/**
*
* #author blj0011
*/
public class JavaFXApplication226 extends Application
{
#Override
public void start(Stage stage) throws Exception
{
Parent root = FXMLLoader.load(getClass().getResource("Controller/Quiz.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);
}
}
Controller:
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.RadioButton;
/**
*
* #author blj0011
*/
public class FXMLDocumentController implements Initializable
{
#FXML
private Label questionLabel;
#FXML
private RadioButton answer_btn1;
#FXML
private RadioButton answer_btn2;
#FXML
private RadioButton answer_btn3;
#FXML
private RadioButton answer_btn4;
#FXML
private Button nextBtn;
#Override
public void initialize(URL url, ResourceBundle rb)
{
// TODO
List<String> questions = new ArrayList();
questions.add("pytanie1");
questions.add("pytanie2");
questions.add("pytanie3");
questions.add("pytanie4");
questions.add("pytanie5");
questions.add("pytanie6");
questions.add("pytanie7");
questions.add("pytanie8");
questions.add("pytanie9");
questions.add("pytanie10");
String[][] answers = new String[1][4];
answers[0][0] = "a) odp";
answers[0][1] = "b) odp";
answers[0][2] = "c) odp";
answers[0][3] = "d) odp";
questionLabel.setText("");
questionLabel.setText(questionLabel.getText() + answers[0][0]);
answer_btn1.setText("aaa");
}
}
FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.RadioButton?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane id="AnchorPane" prefHeight="200" prefWidth="320" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1" fx:controller="javafxapplication226.FXMLDocumentController">
<children>
<Button fx:id="nextBtn" layoutX="118.0" layoutY="161.0" text="Click Me!" />
<Label fx:id="questionLabel" layoutX="124.0" layoutY="36.0" minHeight="16" minWidth="69" />
<RadioButton fx:id="answer_btn1" layoutX="47.0" layoutY="92.0" mnemonicParsing="false" text="RadioButton" />
<RadioButton fx:id="answer_btn2" layoutX="193.0" layoutY="92.0" mnemonicParsing="false" text="RadioButton" />
<RadioButton fx:id="answer_btn3" layoutX="47.0" layoutY="128.0" mnemonicParsing="false" text="RadioButton" />
<RadioButton fx:id="answer_btn4" layoutX="183.0" layoutY="128.0" mnemonicParsing="false" text="RadioButton" />
</children>
</AnchorPane>
I am assuming your project structure looks like the following from your code.

Your issue is that you are instantiating a new controller which is not bound to the view.
You get the controller from the loader like this:
FXMLLoader loader = new FXMLLoader(getClass().getResource("/Controller/Quiz.fxml"));
Parent root = loader.load();
Controller controller = loader.getController();
This way everything will be wired up properly.

Are controller nodes always null inside setOnCloseRequest? [duplicate]

I'm really struggling to understand JavaFX controllers, my aim is to write to a TextArea to act as a log.
My code is below, but I want to be able to change values ETC from another class that I can call when needed. I have tried to create a controller class that extents Initializable but i cant get it to work. Could some one steer me in the correct direction?
I want to move the #FXML code at the bottom to another class and it update the Scene.
package application;
import javafx.event.ActionEvent;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import java.io.IOException;
import javafx.application.Application;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;
public class Main extends Application {
#Override
public void start(Stage primaryStage) {
try {
Parent root = FXMLLoader.load(getClass().getResource("Root.fxml"));
Scene scene = new Scene(root,504,325);
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);
}
public Thread thread = new Thread(new webimporter());
#FXML
public Label runningLabel;
#FXML
public TextArea txtArea;
#FXML
void runClick(ActionEvent event) throws IOException{
changeLabelValue("Importer running...");
thread.start();
}
#FXML
protected void stopClick(ActionEvent event){
changeLabelValue("Importer stopped...");
thread.interrupt();
}
#FXML
void changeLabelValue(String newText){
runningLabel.setText(newText);
}
void changeTextAreaValue(String newText1){
txtArea.setText(newText1);
}
}

Don't make the Application class a controller. It's a sin. There are other questions and answers which address this, but my search skills cannot find them at this time.
The reason it is a sin is:
You are only supposed to have one Application instance, and, by default, the loader will make a new instance, so you end up with two application objects.
Referencing the member objects is confusing, because the original launched application doesn't have the #FXML injected fields, but the loader created application instance does have #FXML inject fields.
Also, unrelated advice: Don't start trying to write multi-threaded code until you have the application at least working to the extent where it displays your UI.
A multi-threaded logger for JavaFX is in the answer to Most efficient way to log messages to JavaFX TextArea via threads with simple custom logging frameworks, though unfortunately it is not straight-forward in its implementation and comes with little documentation.
textlogger/Root.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefWidth="400.0" spacing="10.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="textlogger.ImportController">
<children>
<HBox alignment="BASELINE_LEFT" minHeight="-Infinity" minWidth="-Infinity" spacing="10.0">
<children>
<Button mnemonicParsing="false" onAction="#run" text="Run" />
<Button mnemonicParsing="false" onAction="#stop" text="Stop" />
<Label fx:id="runningLabel" />
</children>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
</HBox>
<TextArea fx:id="textArea" editable="false" prefHeight="200.0" prefWidth="200.0" />
</children>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
</VBox>
textlogger.ImportController.java
package textlogger;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import java.io.IOException;
public class ImportController {
#FXML
private Label runningLabel;
#FXML
private TextArea textArea;
private WebImporter importer;
#FXML
void run(ActionEvent event) throws IOException {
changeLabelValue("Importer running...");
if (importer == null) {
importer = new WebImporter(textArea);
Thread thread = new Thread(
importer
);
thread.setDaemon(true);
thread.start();
}
}
#FXML
void stop(ActionEvent event){
changeLabelValue("Importer stopped...");
if (importer != null) {
importer.cancel();
importer = null;
}
}
private void changeLabelValue(String newText){
runningLabel.setText(newText);
}
}
textlogger.WebImporter.java
import javafx.application.Platform;
import javafx.concurrent.Task;
import javafx.scene.control.TextArea;
import java.time.LocalTime;
public class WebImporter extends Task<Void> {
private final TextArea textArea;
public WebImporter(TextArea textArea) {
this.textArea = textArea;
}
#Override
protected Void call() throws Exception {
try {
while (!isCancelled()) {
Thread.sleep(500);
Platform.runLater(
() -> textArea.setText(
textArea.getText() + LocalTime.now() + "\n"
)
);
}
} catch (InterruptedException e) {
Thread.interrupted();
}
return null;
}
}
textlogger.TextLoggingSample.java
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class TextLoggingSample extends Application {
#Override
public void start(Stage stage) {
try {
FXMLLoader loader = new FXMLLoader();
Parent root = loader.load(
getClass().getResourceAsStream(
"Root.fxml"
)
);
Scene scene = new Scene(root);
stage.setScene(scene);
stage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}

JavaFX Populating a TableView on main screen from a Modal Window form

I am trying to populate a TableView from a method call on the click of a button from a Modal Window. I hope this is possible but I am not having any luck. The TableView is already created in an FXML file. Whenever I call upon the method, I receive a null pointer exception. Any ideas, or suggestions? Sorry if my question format is bad, I don't ask many questions.
MainController.java
#FXML TableView<Part> partsTableView;
#FXML ObservableList<Part> parts;
#FXML public TableColumn<Part, Integer> partIDColumn;
#FXML public TableColumn<Part, String> partNameColumn;
#FXML public TableColumn<Part, Integer> partILColumn;
#FXML public TableColumn<Part, Double> partPriceColumn;
#FXML
public void getPartData(){
partIDColumn.setCellValueFactory(new PropertyValueFactory<>("id")); (Line 112)
partNameColumn.setCellValueFactory(new PropertyValueFactory<>("name"));
partILColumn.setCellValueFactory(new PropertyValueFactory<>("instock"));
partPriceColumn.setCellValueFactory(new PropertyValueFactory<>("price"));
partsTableView.setItems(generateData());
}
private ObservableList<Part> generateData(){
parts = FXCollections.observableArrayList();
parts.add(new Part(0, "Part" , 1 , 25.00));
return parts;
}
main.fxml
<TableView fx:id="partsTableView" layoutX="13.0" layoutY="68.0" prefHeight="344.0" prefWidth="556.0">
<columns>
<TableColumn fx:id="partIDColumn" editable="false" prefWidth="138.0" resizable="false" text="Part ID" />
<TableColumn fx:id="partNameColumn" editable="false" prefWidth="139.0" resizable="false" text="Part Name" />
<TableColumn fx:id="partILColumn" editable="false" prefWidth="119.0" resizable="false" text="Inventory Level" />
<TableColumn fx:id="partPriceColumn" editable="false" prefWidth="159.0" resizable="false" text="Price / Cost Per Unit" />
</columns>
</TableView>
Error: Caused by: java.lang.NullPointerException
at ims.MainController.getPartData(MainController.java:112)
I am using IntelliJ and I build my stage / scene in Scene Builder. I apologize if this is really simple and I'm overlooking something, but, I am just having such a tough time figuring this out.
Thank you in advance for your time and assistance!

I have prepared a sample. You can follow its logic. Main point is to manage main dialog and modal dilog controllers. You can check DialogController dialogController = fxmlLoader.<DialogController>getController(); line in AppMainController.java. In this sample main controller (AppMainController) obtains dialog controller (DialogController) and sets its observablelist to dialog controller. Sample class and fxmls are below:
AppMain.java:
package populatetable;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class AppMain extends Application{
#Override
public void start(Stage primaryStage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("AppMain.fxml"));
Scene scene = new Scene(root, 500,500);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
AppMain.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane minHeight="500.0" minWidth="500.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8.0.111" fx:controller="populatetable.AppMainController">
<children>
<TableView fx:id="tvData" layoutX="91.0" layoutY="159.0" prefHeight="300.0" prefWidth="300.0">
<columns>
<TableColumn fx:id="colId" prefWidth="75.0" text="ID" />
<TableColumn fx:id="colName" prefWidth="75.0" text="Name" />
</columns>
<columnResizePolicy>
<TableView fx:constant="CONSTRAINED_RESIZE_POLICY" />
</columnResizePolicy>
</TableView>
<Button layoutX="211.0" layoutY="85.0" mnemonicParsing="false" onAction="#onOpenDialog" text="Open Dialog" />
</children>
</AnchorPane>
AppMainController.java
package populatetable;
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
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.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.stage.Stage;
public class AppMainController implements Initializable {
#FXML
private TableView<Data> tvData;
#FXML
private TableColumn colId;
#FXML
private TableColumn colName;
private ObservableList<Data> tvObservableList = FXCollections.observableArrayList();
// Open dialog button click event
#FXML
void onOpenDialog(ActionEvent event) throws IOException {
System.out.println("onOpenDialog clicked");
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("Dialog.fxml"));
Parent parent = fxmlLoader.load();
DialogController dialogController = fxmlLoader.<DialogController>getController();
dialogController.setAppMainObservableList(tvObservableList);
Scene scene = new Scene(parent, 300, 200);
Stage stage = new Stage();
stage.setScene(scene);
stage.show();
}
#Override
public void initialize(URL location, ResourceBundle resources) {
colId.setCellValueFactory(new PropertyValueFactory<>("id"));
colName.setCellValueFactory(new PropertyValueFactory<>("name"));
tvData.setItems(tvObservableList);
}
public ObservableList<Data> getTvObservableList() {
return tvObservableList;
}
}
DialogController.java
package populatetable;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
public class DialogController {
private ObservableList<Data> appMainObservableList;
//fill table button click event
#FXML
void fillTable(ActionEvent event) {
Data data = new Data(1, "Name1");
appMainObservableList.add(data);
}
public void setAppMainObservableList(ObservableList<Data> tvObservableList) {
this.appMainObservableList = tvObservableList;
}
}
Dialog.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane minHeight="200.0" minWidth="300.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8.0.111" fx:controller="populatetable.DialogController">
<children>
<Button layoutX="115.0" layoutY="89.0" mnemonicParsing="false" onAction="#fillTable" text="Fill Table" />
</children>
</AnchorPane>
Data.java
package populatetable;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleStringProperty;
public class Data {
private final SimpleIntegerProperty id;
private final SimpleStringProperty name;
public Data(int id, String name) {
this.id = new SimpleIntegerProperty(id);
this.name = new SimpleStringProperty(name);
}
public int getId() {
return id.get();
}
public void setId(int ID) {
id.set(ID);
}
public String getName() {
return name.get();
}
public void setName(String nme) {
name.set(nme);
}
#Override
public String toString() {
return "id: " + id.get() + " - " + "name: " + name.get();
}
}
Hope it is useful.