javaFX-scene builder button event doesn't work - javafx

Question

I'm trying from yesterday javaFX and scene builder in a very simple application to get button click to work, but everything I tried(by following some tutorials or related answers here) it doesn't work.
I created a new javaFX project and these are the files created with my editings:
Main.java:
import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.fxml.FXMLLoader;
public class Main extends Application {
#Override
public void start(Stage primaryStage) {
try {
FXMLLoader loader = new
FXMLLoader(getClass().getResource("sample.fxml"));
loader.setController(new SampleController());
Pane root = loader.load();
Scene scene = new Scene(root,400,400);
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);
}
}
SampleControler.java:
package application;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
public class SampleController implements Initializable{
#FXML
Button bOk;
#FXML
Label lbTest;
private void handleButtonAction(ActionEvent event) {
// Button was clicked, do something...
lbTest.setText("Button Action\n");
}
#Override
public void initialize(URL location, ResourceBundle resources) {
// TODO Auto-generated method stub
bOk.setOnAction(this::handleButtonAction);
}
}
sample.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.Pane?>
<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity"
minWidth="-Infinity" prefHeight="220.0" prefWidth="484.0"
xmlns="http://javafx.com/javafx/8.0.111"
xmlns:fx="http://javafx.com/fxml/1">
<children>
<Button id="bOk" layoutX="214.0" layoutY="152.0"
mnemonicParsing="false" text="Button" />
<Label id="lbTest" layoutX="214.0" layoutY="57.0" prefHeight="25.0"
prefWidth="138.0" text="Label" />
</children>
</Pane>
The above doesn't give any error, but when button clicked it doesn't do anything(supposed to change Label' s text).
I tried to set onAction on fxml file but this always gives error(cannot resolve onAction), no matter what I put there or if I do it from scene builder or by manually edit the fxml file(I have created the method and wrote it correct in onAction).
What I'm doing wrong?
The error I'm getting now:
javafx.fxml.LoadException:
/home/workspace/testapp/bin/application/sample.fxml
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.load(FXMLLoader.java:2409)
at application.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.gtk.GtkApplication._runLoop(Native Method)
at com.sun.glass.ui.gtk.GtkApplication.lambda$null$49(GtkApplication.java:139)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at application.SampleController.initialize(SampleController.java:27)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
After I used fx:id instead of id for button and label the button worked as expected and the above errors gone.

Answer 1

You forgot to use the controller with the fxml:
<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity"
minWidth="-Infinity" prefHeight="220.0" prefWidth="484.0"
xmlns="http://javafx.com/javafx/8.0.111"
xmlns:fx="http://javafx.com/fxml/1"
fx:controller="application.SampleController">
or
FXMLLoader loader = new FXMLLoader(getClass().getResource("sample.fxml"));
loader.setController(new SampleController());
Pane root = loader.load();
Furthermore you need to use fx:id instead of id attributes to inject objects to the controller:
<Button fx:id="bOk" layoutX="214.0" layoutY="152.0"
mnemonicParsing="false" text="Button" />
<Label fx:id="lbTest" layoutX="214.0" layoutY="57.0" prefHeight="25.0"
prefWidth="138.0" text="Label" />