Nullpointer when initializing controller in javafxml application - view

Question

I am not experienced with fxml and lack knowledge at coding in general. So i try to make an fxml application with several labels and textfields. I want a controller to add listeners for all textfields in the initialization so the model will get updated when text is edited in the view. I fail to get the controller to load.
I have tried to initialize the controller, and I've tried to let the fxml loader initialize the controller. Both gives nullpointer exception on the TextField properties. Also when i call loader.getController it returns null.
First time i put code here, sorry if the format is bad
Application class
import javafx.application.Application;
import javafx.collections.ObservableList;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.TextField;
import javafx.stage.Stage;
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception{
Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(root, 300, 275));
primaryStage.show();
FXMLLoader loader = new FXMLLoader(getClass().getResource("sample.fxml"));
Controller c = loader.getController();
System.out.println(c==null);
}
public static void main(String[] args) {
launch(args);
}
}
Parts of FXML class:
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity"
minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0"
xmlns="http://javafx.com/javafx/8.0.172-ea"
xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
<children>
<HBox prefHeight="30.0" prefWidth="600.0">
<children>
<Label prefHeight="30.0" prefWidth="200.0" text="Name" />
<TextField fx:id="name" prefHeight="31.0" prefWidth="198.0" />
<Button fx:id="button" mnemonicParsing="false" prefHeight="31.0" prefWidth="130.0" text="Button">
<HBox.margin>
<Insets left="10.0" />
</HBox.margin>
</Button>
</children>
</HBox>
(...)More Hboxes(...)
Controller class
public class Controller {
Model model;
#FXML private Button button;
#FXML private TextField name;
#FXML private TextField kcal;
public Controller(){
initialize();
}
#FXML
public void initialize(){
model = new Model();
name.textProperty().addListener(((observable, oldValue, newValue)
-> {
model.setName(newValue);
}));
}
Exception in Application start method
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:745)
Caused by: javafx.fxml.LoadException:
"path"/FoodFirebaseWriter/sample/sample.fxml:10
at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2579)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
at sample.Main.start(Main.java:16)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
... 1 more
Caused by: java.lang.NullPointerException
at sample.Controller.initialize(Controller.java:38)
at sample.Controller.<init>(Controller.java:33)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at java.lang.Class.newInstance(Class.java:442)
at sun.reflect.misc.ReflectUtil.newInstance(ReflectUtil.java:51)
at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:927)
at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:971)
at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:220)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:744)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
... 17 more
Exception running application sample.Main

Answer 1

I figured what I did wrong. First the constructor is called, then the #fxml properties are initialized and then the initialize method is called. I called the initialize method in the constructor. Then the #fxml properties are null and the initialize method is called twice. So I just removed the constructor to fix the problem.