Dependency injection with JavaFX gives NullPointerExceptions - spring

Question

I want to mix Java FX and Spring Data. I found video about this problem https://www.youtube.com/watch?v=u0dEf-QN-90&t=3s and I implemented it in my code. In consequence my UI working but I couldn't inject dependency to TaskRepository. I had been trying in difrent ways to inject anything and always I get same error, that my dependency is null. What am I doing wrong?
addingWindow.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.Slider?>
<?import javafx.scene.control.TextArea?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<HBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="pl.projektyjava.listToDoJavaFX.fxmlcontrollers.AddingWindowController">
<children>
<VBox prefHeight="400.0" prefWidth="473.0" HBox.hgrow="ALWAYS">
<children>
<Label alignment="TOP_CENTER" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" text="Tytuł" textAlignment="CENTER" />
<TextField fx:id="title" VBox.vgrow="ALWAYS" />
<Label alignment="TOP_CENTER" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" text="Opis" textAlignment="CENTER" />
<TextArea fx:id="description" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" prefHeight="200.0" prefWidth="200.0" VBox.vgrow="ALWAYS" />
<HBox maxHeight="-Infinity" VBox.vgrow="ALWAYS">
<children>
<Button fx:id="listOfQuest" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" mnemonicParsing="false" text="Lista Zadań" HBox.hgrow="ALWAYS" />
<Button fx:id="addQuest" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" mnemonicParsing="false" text="Dodaj zadanie" HBox.hgrow="ALWAYS" />
</children>
</HBox>
</children>
</VBox>
<Slider fx:id="priority" blockIncrement="1.0" majorTickUnit="1.0" max="5.0" maxHeight="1.7976931348623157E308" maxWidth="1.7976931348623157E308" minorTickCount="0" orientation="VERTICAL" showTickLabels="true" showTickMarks="true" snapToTicks="true" HBox.hgrow="ALWAYS" />
</children>
</HBox>
pl.projektyjava.listToDoJavaFX.appinitialization. Initialization
package pl.projektyjava.listToDoJavaFX.appinitialization;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;
import java.io.IOException;
#Component
public class Initialization implements ApplicationListener<StarterClass.StageReadyEvent>{
#Override
public void onApplicationEvent(StarterClass.StageReadyEvent event) {
Stage stage = event.getStage();
HBox mainPane= null;
try {
mainPane = FXMLLoader.load(getClass().getResource("/addingWindow.fxml"));
} catch (IOException e) {
e.printStackTrace();
}
Scene scene=new Scene(mainPane);
stage.setScene(scene);
stage.show();
}
}
pl.projektyjava.listToDoJavaFX.appinitialization.ListToDoJavaFXApplication
package pl.projektyjava.listToDoJavaFX.appinitialization;
import javafx.application.Application;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class ListToDoJavaFxApplication {
public static void main(String[] args) {
Application.launch(StarterClass.class, args);
}
}
pl.projektyjava.listToDoJavaFX.appinitialization.StarterClass
package pl.projektyjava.listToDoJavaFX.appinitialization;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.stage.Stage;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ApplicationEvent;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.stereotype.Component;
#Component
public class StarterClass extends Application {
private ConfigurableApplicationContext applicationContext;
#Override
public void init() {
applicationContext=new SpringApplicationBuilder(ListToDoJavaFxApplication.class).run();
}
#Override
public void start(Stage stage) {
applicationContext.publishEvent(new StageReadyEvent(stage));
}
#Override
public void stop() {
applicationContext.close();
Platform.exit();
}
static class StageReadyEvent extends ApplicationEvent {
public StageReadyEvent (Stage stage){
super(stage);
}
public Stage getStage(){
return ((Stage) getSource());
}
}
}
pl.projektyjava.listToDoJavaFX.body.Task
package pl.projektyjava.listToDoJavaFX.body;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
#Entity
public class Task {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String title;
private String description;
private double priority;
public Task(String title, String description, double priority) {
this.title = title;
this.description = description;
this.priority = priority;
}
public Task() {
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public double getPriority() {
return priority;
}
public void setPriority(double priority) {
this.priority = priority;
}
}
pl.projektyjava.listToDoJavaFX.body.TaskRepository
package pl.projektyjava.listToDoJavaFX.body;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
#Repository
public interface TaskRepository extends CrudRepository<Task, Long> {
}
pl.projektyjava.listToDoJavaFX.fxmlcontrollers.AddingWindowController
package pl.projektyjava.listToDoJavaFX.fxmlcontrollers;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.Slider;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import pl.projektyjava.listToDoJavaFX.body.Task;
import pl.projektyjava.listToDoJavaFX.body.TaskRepository;
#Controller
public class AddingWindowController {
#Autowired
TaskRepository taskRepository;
#FXML
private TextField title;
#FXML
private TextArea description;
#FXML
private Button listOfQuest;
#FXML
private Button addQuest;
#FXML
private Slider priority;
public void initialize() {
addQuest.setOnAction(event -> {
String titleText = title.getText();
String descriptionText = description.getText();
double priorityVal = priority.getValue();
Task task = new Task(titleText, descriptionText, priorityVal);
taskRepository.save(task);
});
}
}
and ERROR:
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException: Cannot invoke "pl.projektyjava.listToDoJavaFX.body.TaskRepository.save(Object)" because "this.taskRepository" is null
at pl.projektyjava.listToDoJavaFX.fxmlcontrollers.AddingWindowController.lambda$initialize$0(AddingWindowController.java:41)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:234)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8792)
at javafx.scene.control.Button.fire(Button.java:203)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:208)
at com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:247)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:234)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3861)
at javafx.scene.Scene.processMouseEvent(Scene.java:1854)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2587)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:409)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:299)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:447)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:413)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:446)
at com.sun.glass.ui.View.handleMouseEvent(View.java:556)
at com.sun.glass.ui.View.notifyMouse(View.java:942)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
After adding ControlerFactory to FXMLLoader I have this:
javafx.fxml.LoadException:
/B:/Projekty/1%20PROJEKT/listToDo-JavaFX/listToDo-JavaFX/target/classes/addingWindow.fxml:11
at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2707)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2685)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2517)
at pl.projektyjava.listToDoJavaFX.appinitialization.Initialization.onApplicationEvent(Initialization.java:28)
at pl.projektyjava.listToDoJavaFX.appinitialization.Initialization.onApplicationEvent(Initialization.java:14)
at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176)
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143)
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:421)
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:378)
at pl.projektyjava.listToDoJavaFX.appinitialization.StarterClass.start(StarterClass.java:26)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:849)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:474)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:447)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:446)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
at java.base/java.lang.Thread.run(Thread.java:831)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'pl.projektyjava.listToDoJavaFX.fxmlcontrollers.AddingWindowController' available
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:351)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:342)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1172)
at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:940)
at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:982)
at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:229)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:754)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2808)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2634)
... 19 more
Exception in Application start method
Exception in thread "main" java.lang.RuntimeException: Exception in Application start method
2021-04-23 19:47:00.791 INFO 12928 --- [lication Thread] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2021-04-23 19:47:00.794 INFO 12928 --- [lication Thread] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Shutdown initiated...
2021-04-23 19:47:00.800 INFO 12928 --- [lication Thread] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Shutdown completed.
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:903)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:198)
at java.base/java.lang.Thread.run(Thread.java:831)
Caused by: java.lang.NullPointerException: Root cannot be null
at javafx.scene.Scene.<init>(Scene.java:345)
at javafx.scene.Scene.<init>(Scene.java:207)
at pl.projektyjava.listToDoJavaFX.appinitialization.Initialization.onApplicationEvent(Initialization.java:32)
at pl.projektyjava.listToDoJavaFX.appinitialization.Initialization.onApplicationEvent(Initialization.java:14)
at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176)
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143)
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:421)
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:378)
at pl.projektyjava.listToDoJavaFX.appinitialization.StarterClass.start(StarterClass.java:26)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:849)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:474)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:447)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:446)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
... 1 more
Process finished with exit code 1

Answer 1

By default, the FXMLLoader will create controller instances by calling the no-argument constructor. Consequently, the AddingWindowController instance that's created is not managed by Spring, and Spring cannot inject #Autowired dependencies into it. (Basically, the Spring ApplicationContext has no knowledge that the AddingWindowController instance exists.)
You can supply a ControllerFactory to the FXMLLoader which asks that the controller is created by the spring application context:
#Component
public class Initialization implements ApplicationListener<StarterClass.StageReadyEvent>{
#Autowired
private ApplicationContext applicationContext ;
#Override
public void onApplicationEvent(StarterClass.StageReadyEvent event) {
Stage stage = event.getStage();
HBox mainPane= null;
try {
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("/addingWindow.fxml"));
fxmlLoader.setControllerFactory(applicationContext::getBean);
mainPane = fxmlLoader.load();
} catch (IOException e) {
e.printStackTrace();
}
Scene scene=new Scene(mainPane);
stage.setScene(scene);
stage.show();
}
}
Also note that you should create a new controller instance each time the FXML is loaded, so JavaFX controllers should have prototype scope. It probably doesn't matter too much, but the #Controller annotation in Spring is really intended for MVC controllers in a web application, so the #Component stereotype is really more appropriate here:
#Component
#Scope("prototype")
public class AddingWindowController {
// ...
}

Answer 2

By default #SpringBootApplication does componentscan in its own folder and underneath. So just place ur ListToDoJavaFxApplication one folder up into pl.projektyjava.listToDoJavaFX
Alternatively just add #ComponentScan(“pl.projektyjava.listToDoJavaFX”) right above #SpringBootApplication defining component scan explicitly.
In general whenever auto wiring fails silently without BeanCreationException at startup it is a sign that ur component is not being found by component scan