How to load new FXML with another controller class in the same scene

Question

I've tried to load new FXML by

URL url = this.getClass().getClassLoader().getResource("pknn/fxml/CreateCharacter.fxml");if (url == null) return;
AnchorPane pane = FXMLLoader.load(url);
startPanel.getChildren().setAll(pane);

Which is worked for CreateCharacter.fxml with StartController

<AnchorPane fx:id="createCharacterPanel" onMouseEntered="#paneEventHandler" prefHeight="600.0" prefWidth="800.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="pknn.StartController">

But when I try to load another FXML to the same scene

URL url = this.getClass().getClassLoader().getResource("pknn/fxml/LockerRoom.fxml");
if (url == null) return;
AnchorPane pane = FXMLLoader.load(url);
createCharacterPanel.getChildren().setAll(pane);

it doesn't work, even I change it to

startPanel.getChildren().setAll(pane);

But it still not work. This is the fxml I want to load.

<AnchorPane fx:id="lockerRoomPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="pknn.LockerRoomController">

it come with so many exception like

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
...
Caused by: javafx.fxml.LoadException: 
/Users/pknn/Study/ComPro/MonsterBattle/out/production/MonsterBattle/pknn/fxml/LockerRoom.fxml:10

at pknn.StartController.createCharacter(StartController.java:132)
Caused by: java.lang.IllegalAccessException: Class sun.reflect.misc.ReflectUtil can not access a member of class pknn.LockerRoomController with modifiers ""

How to fix it? Thanks

Answer 1

You cannot "override" the controller specified in the FXML. If you plan to change the controller (or have a controller with constructor parameters) then you have to remove the fx:controller attribute from the FXML and set the controller in the FxmlLoader:

        fxmlLoader = new FXMLLoader(fxmlFileAsResource);
        fxmlLoader.setController(yourControllerInstance);
        Pane pane = fxmlLoader.load();

Answer 2

This is an example of loading different FXML frames in the same Scene

create_character.fxml

<AnchorPane fx:id="createCharacterPanel" fx:controller="sample.StartController" xmlns:fx="http://javafx.com/fxml" >
    <children>
        <Button text="Load" onAction="#handleLoadFXML" AnchorPane.topAnchor="0" AnchorPane.leftAnchor="0" />
        <ScrollPane AnchorPane.topAnchor="30" AnchorPane.leftAnchor="0" AnchorPane.rightAnchor="0" AnchorPane.bottomAnchor="0">
            <content>
                <VBox fx:id="child"/>
            </content>
        </ScrollPane>
    </children>
</AnchorPane>

pane_a.fxml and pane_b.fxml

<AnchorPane xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml" fx:controller="sample.SecondController">
    <children>
        <Label text="Pane A"/>
    </children>
</AnchorPane>

<AnchorPane xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml" fx:controller="sample.SecondController">
    <children>
        <Label text="Pane B"/>
    </children>
</AnchorPane>

The controller that loads the files

public class StartController {
    @FXML
    private AnchorPane createCharacterPanel;

    @FXML
    private VBox child;

    private Parent loadFXML(String name) {
        try {
            return FXMLLoader.load(getClass().getResource(name));
        }
        catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    @FXML
    private void handleLoadFXML(ActionEvent event) {
        child.getChildren().addAll(
            loadFXML("pane_a.fxml"),
            loadFXML("pane_b.fxml")
        );
    }
}