Javafx can't show main window fxml after login - javafx

Question

im devlop javaFx login app from tutorial on youtube for school homework. but after click login button. the login function can't show window main scene (AdminLayout.fxml). just login window hide. Thank you
this is my Error
Caused by: 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 sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
... 45 more
Caused by: java.lang.NullPointerException
at mpn.manda.controller.LoginLayoutController.Login(LoginLayoutController.java:58)
... 55 more
line 58 at LoginLayoutController.java
Pane p = fxmlLoader.load(getClass().getResource("view/AdminLayout.fxml").openStream());
File LoginLayoutController.java
package mpn.manda.controller;
import java.io.IOException;
import java.net.URL;
import java.sql.SQLException;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.Initializable;
import mpn.manda.model.LoginModel;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;
/**
* FXML Controller class
*
* #author Xaxxis
*/
public class LoginLayoutController implements Initializable {
public LoginModel loginModel = new LoginModel();
#FXML
private Label isConnected;
#FXML
private TextField usernameField;
#FXML
private PasswordField passwordField;
#Override
public void initialize(URL location, ResourceBundle resource) {
if (loginModel.isDbConnected()) {
isConnected.setText("Connected");
} else {
isConnected.setText("Not Connected");
}
}
public void Login (ActionEvent event) {
try {
if (loginModel.isLogin(usernameField.getText(), passwordField.getText())) {
((Node)event.getSource()).getScene().getWindow().hide();
Stage primaryStage = new Stage();
FXMLLoader fxmlLoader = new FXMLLoader();
Pane p = fxmlLoader.load(getClass().getResource("view/AdminLayout.fxml").openStream());
AdminLayoutController adminController = (AdminLayoutController)fxmlLoader.getController();
adminController.GetUser(usernameField.getText());
Scene scene = new Scene(p);
scene.getStylesheets().add(getClass().getResource("css/application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
} else {
isConnected.setText("Username and password is not correct");
}
} catch (SQLException e) {
isConnected.setText("Username and password is not correct");
}
catch(IOException e) {
e.printStackTrace();
}
}
}
MainApp.java
package mpn.manda;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
/**
*
* #author Xaxxis
*/
public class MainApp extends Application {
#Override
public void start(Stage primaryStage) {
try {
Parent root = FXMLLoader.load(getClass().getResource("view/LoginLayout.fxml"));
Scene scene = new Scene(root);
scene.getStylesheets().add(getClass().getResource("css/application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
}
</pre>
AdminLayoutController.java
<pre>
package mpn.manda.controller;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
/**
* FXML Controller class
*
* #author Xaxxis
*/
public class AdminLayoutController implements Initializable {
#FXML
private Label userLabel;
#Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
}
public void GetUser(String user) {
// TODO
userLabel.setText(user);
}
public void Logout(ActionEvent event) {
}
}
LoginLayout.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import java.net.URL?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.PasswordField?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.paint.RadialGradient?>
<?import javafx.scene.paint.Stop?>
<?import javafx.scene.text.Font?>
<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" styleClass="mainFxmlClass" xmlns="http://javafx.com/javafx/8.0.65" xmlns:fx="http://javafx.com/fxml/1" fx:controller="mpn.manda.controller.LoginLayoutController">
<stylesheets>
<URL value="#/mpn/manda/css/application.css" />
</stylesheets>
<children>
<Label fx:id="isConnected" layoutX="18.0" layoutY="94.0" prefHeight="28.0" prefWidth="485.0" text="Status" textFill="#f20202">
<font>
<Font size="15.0" />
</font>
</Label>
<Label layoutX="94.0" layoutY="135.0" text="Username" />
<Label layoutX="94.0" layoutY="183.0" text="Password" />
<TextField fx:id="usernameField" layoutX="203.0" layoutY="130.0" promptText="Your username" />
<PasswordField fx:id="passwordField" layoutX="203.0" layoutY="178.0" promptText="Your password" />
<Button layoutX="203.0" layoutY="236.0" mnemonicParsing="false" onAction="#Login" prefHeight="27.0" prefWidth="78.0" text="Login..." />
<Button layoutX="288.0" layoutY="236.0" mnemonicParsing="false" prefHeight="27.0" prefWidth="78.0" text="Cancel" />
<Label layoutX="47.0" layoutY="24.0" prefHeight="59.0" prefWidth="381.0" text="Welcom To The App">
<font>
<Font size="31.0" />
</font>
<textFill>
<RadialGradient centerX="0.5" centerY="0.5" radius="0.5">
<stops>
<Stop color="#3c361c" />
<Stop color="#9a8d8d" offset="0.9330855018587361" />
<Stop color="#9a8d8d" offset="1.0" />
</stops>
</RadialGradient>
</textFill>
</Label>
</children>
</AnchorPane>
AdminLayout.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.BorderPane?>
<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.65" xmlns:fx="http://javafx.com/fxml/1" fx:controller="mpn.manda.controller.AdminLayoutController">
<top>
<Label fx:id="userLabel" prefHeight="17.0" prefWidth="154.0" text="Halo, " BorderPane.alignment="CENTER" />
</top>
<bottom>
<Button mnemonicParsing="false" text="Logout.." BorderPane.alignment="CENTER" />
</bottom>
</BorderPane>

Answer 1

The path is wrong.
getClass().getResource("view/AdminLayout.fxml")
will resolve the path relative to the current class (so it is looking for /mpn/manda/controller/view/AdminLayout.fxml). Assuming (since the resource works correctly in MainApp) the view package is mpn.manda.view (i.e. AdminLayout.fxml and LoginLayout.fxml are in the same package), you can either do
getClass().getResource("/mpn/manda/view/AdminLayout.fxml")
(note the leading /, which resolves relative to the classpath), or
MainApp.class.getResource("view/AdminLayout.fxml")
which will resolve the path relative to the MainApp class.
Do not be tempted to use .. to reference a "parent package": this might work when you are reading resources and classes from the file system (e.g. during development), but will fail if your application is bundled in a jar file (which it will be at production time).
As an aside, you should prefer loading the FXML by specifying the URL of the FXML resource, instead of the stream. This is because any resource resolutions in the FXML file itself will fail if you do not specify a URL to the FXMLLoader. So I recommend
FXMLLoader fxmlLoader = new FXMLLoader(MainApp.class.getResource("view/AdminLayout.fxml"));
Pane p = fxmlLoader.load();
// ...
If you like the structure where you have one package (view) for the FXML files and one (controller) for the controllers (I don't, FWIW), another technique you might like is to define an empty class for the purpose of resolving view resources:
package mpn.manda.view ;
public abstract class View { }
And now you can load any FXML from anywhere with
FXMLLoader loader = new FXMLLoader(View.class.getResource("LoginLayout.fxml"));
Parent root = loader.load();
and
FXMLLoader loader = new FXMLLoader(View.class.getResource("AdminLayout.fxml"));
Parent p = loader.load();
etc. etc.