Why I'm getting javafx.fxml.LoadException even the path of the fxml file is correct

Question

I get

javafx.fxml.LoadException:

When I'm loading and fxml file using following line of code.

AnchorPane anchorPane = (AnchorPane)loader.load()

This is my fxml file excluding import statements.

<AnchorPane prefHeight="537.0" prefWidth="374.0"     xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.buddhikajay.controller.NewTransactionDialogController">
   <children>
      <GridPane hgap="5.0" layoutX="30.0" layoutY="10.0" prefHeight="544.0" prefWidth="314.0" vgap="5.0">
    <columnConstraints>
      <ColumnConstraints hgrow="SOMETIMES" maxWidth="142.0" minWidth="10.0" prefWidth="69.0" />
      <ColumnConstraints hgrow="SOMETIMES" maxWidth="226.0" minWidth="10.0" prefWidth="225.0" />
    </columnConstraints>
    <rowConstraints>
      <RowConstraints maxHeight="70.0" minHeight="10.0" prefHeight="33.0" vgrow="SOMETIMES" />
      <RowConstraints maxHeight="105.0" minHeight="10.0" prefHeight="38.0" vgrow="SOMETIMES" />
      <RowConstraints maxHeight="156.0" minHeight="10.0" prefHeight="51.0" vgrow="SOMETIMES" />
        <RowConstraints maxHeight="154.0" minHeight="10.0" prefHeight="43.0" vgrow="SOMETIMES" />
        <RowConstraints maxHeight="160.0" minHeight="10.0" prefHeight="43.0" vgrow="SOMETIMES" />
        <RowConstraints maxHeight="161.0" minHeight="10.0" prefHeight="63.0" vgrow="SOMETIMES" />
        <RowConstraints maxHeight="301.0" minHeight="10.0" prefHeight="180.0" vgrow="SOMETIMES" />
        <RowConstraints maxHeight="231.0" minHeight="10.0" prefHeight="106.0" vgrow="SOMETIMES" />
    </rowConstraints>
     <padding>
        <Insets bottom="5.0" left="5.0" right="5.0" top="5.0" />
     </padding>
     <children>
        <Label text="ID" />
        <Label text="Date" GridPane.rowIndex="1" />
        <Label text="Amont" GridPane.rowIndex="2" />
        <Label text="Person" GridPane.rowIndex="4" />
        <Label text="Type" GridPane.rowIndex="3" />
        <Label text="Resolved" GridPane.rowIndex="5" />
        <Label />
        <Label text="Description" GridPane.rowIndex="6" />
        <TextField fx:id="idTextField" GridPane.columnIndex="1" />
        <TextField fx:id="dateTextField" GridPane.columnIndex="1" GridPane.rowIndex="1" />
        <TextField fx:id="amountTextField" GridPane.columnIndex="1" GridPane.rowIndex="2" />
        <TextArea fx:id="descriptionTextArea" prefHeight="200.0" prefWidth="200.0" GridPane.columnIndex="1" GridPane.rowIndex="6" />
        <HBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="50.0" prefWidth="225.0" spacing="20.0" GridPane.columnIndex="1" GridPane.rowIndex="7">
           <GridPane.margin>
              <Insets />
           </GridPane.margin>
           <padding>
              <Insets bottom="10.0" left="20.0" right="10.0" top="10.0" />
           </padding>
           <children>
              <Button fx:id="okButton" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" mnemonicParsing="false" onAction="#okActionFired" prefHeight="25.0" prefWidth="75.0" text="Ok" />
              <Button fx:id="cancleButton" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" mnemonicParsing="false" onAction="#cancleActionFired" prefHeight="25.0" prefWidth="75.0" text="Cancle" />
           </children>
        </HBox>
        <ComboBox fx:id="typeComboBox" prefWidth="150.0" GridPane.columnIndex="1" GridPane.rowIndex="3" />
        <ComboBox fx:id="personComboBox" prefWidth="150.0" GridPane.columnIndex="1" GridPane.rowIndex="4" />
        <ComboBox fx:id="resolvedComboBox" prefWidth="150.0" GridPane.columnIndex="1" GridPane.rowIndex="5" />
     </children>
  </GridPane>
  </children>
</AnchorPane>

The compiler complains that there is an error in line number 1. I'm sure that the path of fxml file is correct. What is wrong with my code?

Here is the full error stack

javafx.fxml.LoadException: 
/C:/Users/Buddhika/Documents/Programming/IdeaProjects/VirtualCreditDesktop/out/production/VirtualCreditDesktop/com/buddhikajay/view/NewTransactionDialog.fxml:9

    at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2595)
    at javafx.fxml.FXMLLoader.access$700(FXMLLoader.java:104)
    at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:928)
    at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:967)
    at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:216)
    at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:740)
    at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2701)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2521)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2435)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2403)
    at com.buddhikajay.controller.NewTransactionDialogController.showNewTransactionDialog(NewTransactionDialogController.java:68)
    at com.buddhikajay.controller.MainApp.start(MainApp.java:51)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$153(LauncherImpl.java:821)
    at com.sun.javafx.application.LauncherImpl$$Lambda$50/1976027283.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$166(PlatformImpl.java:323)
    at com.sun.javafx.application.PlatformImpl$$Lambda$46/301541210.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$164(PlatformImpl.java:292)
    at com.sun.javafx.application.PlatformImpl$$Lambda$48/474926796.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$165(PlatformImpl.java:291)
    at com.sun.javafx.application.PlatformImpl$$Lambda$47/1662429848.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$141(WinApplication.java:102)
    at com.sun.glass.ui.win.WinApplication$$Lambda$38/519284171.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.InstantiationException: com.buddhikajay.controller.NewTransactionDialogController
    at java.lang.Class.newInstance(Class.java:423)
    at sun.reflect.misc.ReflectUtil.newInstance(ReflectUtil.java:51)
    at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:923)
    ... 23 more
Caused by: java.lang.NoSuchMethodException: com.buddhikajay.controller.NewTransactionDialogController.<init>()
    at java.lang.Class.getConstructor0(Class.java:3074)
    at java.lang.Class.newInstance(Class.java:408)
    ... 25 more

Answer 1

The problem is described in the stack trace:

Caused by: java.lang.NoSuchMethodException: com.buddhikajay.controller.NewTransactionDialogController.()

which basically says your controller class doesn't have a zero-argument constructor.

By default, the FXMLLoader will create the controller by calling its zero-argument constructor. Remove the constructor that you have defined in the controller class, or remove the parameters that it takes.

If you really need to pass arguments to the controller's constructor, you can either create the controller in Java code and pass it to the FXMLLoader:

NewTransactionDialogController controller = new NewTransactionDialogController(someValue);
FXMLLoader loader = new FXMLLoader();
loader.setLocation(...);
loader.setController(controller);
AnchorPane anchorPane = loader.load();

(Using this code, you must remove the fx:controller attribute from the FXML.)

Or, set a controller factory:

FXMLLoader loader = new FXMLLoader();
loader.setLocation(...);
loader.setControllerFactory(clazz -> {
    if (clazz == NewTransactionDialogController.class) {
        return new NewTransactionDialogController(someValue);
    } else {
        // default behavior:
        try {
            return clazz.newInstance();
        } catch (Exception exc) {
            throw new RuntimeException(exc);
        }
    }
});

AnchorPane anchorPane = loader.load();

(In this version, leave the fx:controller attribute in the FXML file.)