JavaFX Dialogbox communication - java

I am new to JavaFX and trying to create an Confirmation Dialogbox.
I know already that there is no real build in dialogbox in JavaFX so I created one myself like this:
#FXML
public void delBox() {
try {
Stage dialogStage = new Stage();
AnchorPane root = FXMLLoader.load(getClass().getResource("Dialog.fxml"));
Scene scene = new Scene(root);
dialogStage.setScene(scene);
dialogStage.showAndWait();
} catch(Exception e) {
e.printStackTrace();
}
}
It looks pretty good already, but what I dont understand is, how those two Stages can communicate with each other? I want to pass a String to the dialog which is than shown in the message, also when one of the buttons in the dialog window is clicked I wanna react to this in the accordingly.
Can anyone explain me how communication between the stages works?
btw: I use .FXML files and controller classes.

You need a reference to the controller for the dialog. To do this, create an instance of FXMLLoader instead of using the static FXMLLoader.load(URL) method.
For example, suppose you have a class DialogController, so your Dialog.fxml looks like:
<AnchorPane xmlns:fx="..." fx:controller="DialogController.fxml">
...
</AnchorPane>
Then you can access the DialogController in the delBox() method above with
Stage dialogStage = new Stage();
FXMLLoader loader = new FXMLLoader(getClass().getResource("Dialog.fxml"));
AnchorPane root = (AnchorPane)loader.load();
DialogController controller = (DialogController) loader.getController();
Scene scene = new Scene(root);
dialogStage.setScene(scene);
dialogStage.showAndWait();
And now you can communicate between the two controllers. For example, in DialogController you could define a message property, and bind it to a Label :
public class DialogController {
private final StringProperty message = new SimpleStringProperty("");
public void setMessage(String message) {
this.message.set(message);
}
public String getMessage() {
return message.get();
}
public StringProperty messageProperty() {
return message ;
}
#FXML
private Label label ;
public void initialize() {
label.textProperty().bind(message);
// ...
}
}
And then back in your delBox() method:
//... as before:
AnchorPane root = (AnchorPane)loader.load();
DialogController controller = (DialogController) loader.getController();
controller.setMessage("Hello World");
// ...
Similarly, you can define properties which are set when controls are pressed in the dialog itself, and either observe them or query them after the showAndWait() call.
There are a bunch of other similar techniques. Some examples:
https://github.com/james-d/Shared-Data-Controller/tree/master/src
https://github.com/james-d/Dialog-FXML-Example/tree/master/src
https://github.com/james-d/Nested-Controller-Example/tree/master/src/nestedcontrollerexample

<AnchorPane xmlns:fx="..." fx:controller="DialogController.fxml">
...
</AnchorPane>
FX Controller is a java file, so it has to be DialogController and the Controller's path should be included i.e, fx:controller="applicationPackageName.DialogController"
The above mentioned fxml code does not work. It results in
javafx.fxml.LoadException
java.lang.InstantiationException
java.lang.NoSuchMethodException
Reason: The jvm looks for a class constructor with 0 parameters to build an instance. To overcome the error, the controller file needs to be loaded in the function coded in java:
loader.setController(new ControllerName(""));
To sum up (Working code):
FXML file:
<BorderPane id="background" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="240.0" prefWidth="320.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" >
<bottom>
<HBox alignment="CENTER" prefHeight="100.0" prefWidth="200.0">
<children>
<Button onAction="#close" text="OK" />
</children>
</HBox>
</bottom>
<center>
<Label fx:id="messageLabel" />
</center>
</BorderPane>
Controller file:
public class PiPreferenceController {
private final String message ;
#FXML
private Label messageLabel ;
#FXML
void initialize() {
messageLabel.setText(message);
}
public PiPreferenceController(String message) {
this.message = message ;
}
#FXML
public void close() {
messageLabel.getScene().getWindow().hide();
}
}
Function:
void dialogPreferences() throws IOException {
Stage dialogStage = new Stage();
FXMLLoader loader = new FXMLLoader(getClass().getResource(
"PiPreference.fxml"));
loader.setController(new PiPreferenceController(""));
BorderPane root = (BorderPane) loader.load();
Scene scene = new Scene(root);
dialogStage.setScene(scene);
dialogStage.showAndWait();
}

Related

Interact between several FXMLs

I'm trying to write my first application with javaFX and FXML files, but I got stuck with accesing variables of the FXMLs.
I am able to start the program with the first scene (first FXML). There is a button I'm able to interact with, and the first scene hides and the second scene appears. In that scene, the user has to insert a value in a text field. I'm able to save this into a variable by confirming this input over another button.
This button click hides the second scene and opens the first scene again. Now I want to set the value of a label in that first scene to the value of the variable I saved the user's input in. But this throws an error message.
It seems like this label value is not accessable, even if this label is part of the currently loaded FXML, but I am able to get the value of a label of the second FXML (user interaction field), which isn't visible anymore.
Can anyone help me, how to make this Label of the first FXML readable and changable?
My code is quite long, but I tired to give you the most important parts:
#FXML
private Label RollsMax;
#FXML
private TextField roll_input;
#FXML
private String amountRolls;
... // several more declarations
#FXML
void btn_confirmInput_onClick(ActionEvent event){ //btn_confirmInput is part of scene2.fxml
event.consume();
amountRolls=roll_input.getText();
System.out.println(amountRolls); // here I get the result of the user's input
try{
root=FXMLLoader.load(getClass().getResource("project/scene1.fxml"));
stage=(Stage)((Node)event.getSource()).getScene().getWindow();
scene=new Scene(root);
stage.setScene(scene);
stage.show();
} //end try
catch (IOException e){
e.printStackTrace();
} //end catch
RollsMax.setText(amountRolls); // THIS LINE IS NOT WORKING AS RollsMax SEEMS NOT AVAILABLE, EVEN IF IT IS PART OF SCENE1.fxml
} // end btn_confirmInput_onClick()
Any ideas? The error I get is 'java.lang.RuntimeException: java.lang.reflect.InvocationtargetException' as well as a'java.lang.NullPointerException'.
Thanks a lot!
Endcoder
To share data between the scenes, we'll introduce a Model class that holds the shared information:
public class Model {
private SimpleStringProperty valueProperty = new SimpleStringProperty("N/A");
public SimpleStringProperty getValueProperty() {
return valueProperty;
}
}
And an interface to be implemented by the controllers of the two scenes (actually the controllers of the two roots of the two scenes).
The interface adds the functionality of injection a Model into the controller:
public interface Controller {
void setModel(Model model);
}
sceneOne.fxml with a button to switch scene and a label to display user's input:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>
<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity"
prefHeight="300.0" prefWidth="400.0" xmlns="http://javafx.com/javafx/16"
xmlns:fx="http://javafx.com/fxml/1" fx:controller="SceneOneController">
<children>
<Label layoutX="159.0" layoutY="40.0" text="Scene 1">
<font>
<Font size="24.0" />
</font>
</Label>
<Button layoutX="264.0" layoutY="246.0" mnemonicParsing="false" onAction="#changeScene" prefHeight="26.0" prefWidth="102.0" text="Get Input" />
<Label fx:id="inputValue" layoutX="187.0" layoutY="142.0" text="Label" />
</children>
</AnchorPane>
And its controller which implements the Controller interface:
public class SceneOneController implements Controller {
#FXML Label inputValue;
private Model model;
public void changeScene(ActionEvent e) {
try {
FXMLLoader loader = new FXMLLoader(getClass().getResource("sceneTwo.fxml"));
Parent root = loader.load();
Controller controller = loader.getController(); //get a reference to sceneTwo controller
controller.setModel(model);
Stage stage = (Stage)((Node)e.getSource()).getScene().getWindow();
stage.setScene(new Scene(root));
} catch (Exception ex) {
ex.printStackTrace();
}
}
#Override
public void setModel(Model model) {
this.model = model;
if(model != null){
inputValue.textProperty().unbind();
inputValue.textProperty().bind(model.valueProperty);
}
}
}
sceneTwo.fxml with a button to switch scene and a TextField for the user's input:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>
<AnchorPane fx:id="main" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="300.0" prefWidth="400.0" xmlns="http://javafx.com/javafx/16" xmlns:fx="http://javafx.com/fxml/1" fx:controller="SceneTwoController">
<children>
<Label layoutX="150.0" layoutY="41.0" text="Scene 2">
<font>
<Font size="24.0" />
</font>
</Label>
<Button layoutX="264.0" layoutY="246.0" mnemonicParsing="false" onAction="#changeScene" prefHeight="26.0" prefWidth="102.0" text="Update" />
<TextField fx:id="inputValue" layoutX="121.0" layoutY="138.0" prefHeight="25.0" prefWidth="162.0" />
</children>
</AnchorPane>
And its controller:
public class SceneTwoController implements Controller {
#FXML TextField inputValue;
private Model model;
public void changeScene(ActionEvent e) {
try {
FXMLLoader loader = new FXMLLoader(getClass().getResource("sceneOne.fxml"));
Parent root = loader.load();
Controller controller = loader.getController(); //get a reference to sceneOne controller
controller.setModel(model);
Stage stage = (Stage)((Node)e.getSource()).getScene().getWindow();
stage.setScene(new Scene(root));
} catch (Exception ex) {
ex.printStackTrace();
}
}
#Override
public void setModel(Model model) {
this.model = model;
if(model != null){
inputValue.textProperty().unbind();
model.valueProperty.bind(inputValue.textProperty());
}
}
}
And finally the application to test it all:
public class SwitchSceneMVC extends Application {
#Override
public void start(Stage primaryStage) throws Exception{
FXMLLoader loader = new FXMLLoader(getClass().getResource("sceneOne.fxml"));
Parent root = loader.load();
Model model = new Model();
Controller controller = loader.getController();
controller.setModel(model);
primaryStage.setScene(new Scene(root));
primaryStage.show();
}
public static void main(String[] args) {
launch(null);
}
}
Use a controller class for every FXML. Then you should be able to interact between them with public methods.
Especially when just hidinng the first scene you should then be able to just write from one scene to the other one.
Alternatively: while starting the second scene make a parameter where you bring the instance of the first scene. Than you should be able to use the needed methods on the first scenes instance.
Like
Code Scene one
#FXML
private void startSceneTwoButton(){
new SceneTwo(this);
}
Code Scene two
FirstScene scene;
public SecondScene(FirstScene scene){
this.scene = scene;
//some code
}
#FXML
private void button(){
scene.enterValue(value);
}

Null Pointer Exception when using Scroll pane javafX

I've been building a cinema booking application and am trying to create a scene that displays movies and showing times. It works when I have used an anchor pane and vbox to display all the information but when I try to insert an additional scroll pane (in scenebuilder) the FXML loader returns a null pointer exception and I cant work out why...
Here is my FXML code
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<AnchorPane prefHeight="598.0" prefWidth="798.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="MovieShowingsController">
<children>
<MenuBar>
<menus>
<Menu mnemonicParsing="false" text="myBookings">
<items>
<MenuItem mnemonicParsing="false" text="Close" />
</items>
</Menu>
</menus>
</MenuBar>
<ScrollPane fx:id="scrollpane" hbarPolicy="NEVER" layoutY="22.0" prefHeight="576.0" prefWidth="798.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="22.0">
<content>
<VBox fx:id="vbox" prefHeight="555.0" prefWidth="740.0" />
</content>
</ScrollPane>
</children>
</AnchorPane>
Here is the controller class
public class MovieShowingsController {
#FXML
private VBox vbox;
private ArrayList<FilmInfo> filmList;
private ArrayList<Screening> screeningList;
private MovieShowings showings;
//FXML loader instance variable to be accessed by dynamic scene controller
private VBox holder;
#FXML
private void initialize() {
}
public MovieShowingsController() {
}
public MovieShowingsController(MovieShowings showings) {
String date = "2019-04-15";
Date sqlDate = Date.valueOf(date);
System.out.println("\n");
System.out.println("***Screenings for " + date + "***");
filmList = new ArrayList();
screeningList = DatabaseConnection.getInstance().retrieveScreeningsForDay(sqlDate);
for (Screening screeningInstance : screeningList) {
if (!filmList.contains(screeningInstance.getFilmInfo())) {
filmList.add(screeningInstance.getFilmInfo());
}
System.out.println(screeningInstance.toString());
}
Collections.sort(screeningList);
this.showings = showings;
//populating FXML instance variable from loader
this.holder = (VBox) showings.getRoot().lookup("#vbox");
buildMovieShowings(holder);
}
private void buildMovieShowings(VBox holder) {
holder.setSpacing(50);
for (int i = 0; i < filmList.size(); i++) {
VBox infoHolder = new VBox();
infoHolder.setSpacing(10);
Label title = new Label(String.format("%s%8s", filmList.get(i).getTitle(),
"(" + filmList.get(i).getRating() + ")"));
title.setStyle("-fx-font: 24 arial;");
Label duration = new Label(String.format("%s%s%s", "Film Length: ",
filmList.get(i).getDuration(), " mins"));
duration.setStyle("-fx-font: 24 arial;");
Label director = new Label(String.format("%s%s", "Directed By: ",
filmList.get(i).getDirector()));
director.setStyle("-fx-font: 24 arial;");
infoHolder.getChildren().addAll(title, duration, director);
HBox timesHolder = new HBox();
timesHolder.setSpacing(10);
for (int j = 0; j < screeningList.size(); j++) {
if (screeningList.get(j).getFilmInfo().equals(filmList.get(i))){
Label time = new Label();
Background black = new Background(new BackgroundFill(Color.BLACK, CornerRadii.EMPTY, Insets.EMPTY));
Background red = new Background(new BackgroundFill(Color.RED, CornerRadii.EMPTY, Insets.EMPTY));
time.setBackground(black);
Screen screen = screeningList.get(j).getScreen();
Screening screening = screeningList.get(j);
time.setOnMouseClicked(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent e) {
try {
System.out.println(screening.getFilmInfo().getTitle() + screening.getShowTime());
time.setBackground(red);
SeatMap seatMap = new SeatMap();
SeatMapController seatMapController = new SeatMapController(seatMap,
screen);
Scene seatMapScene = seatMap.getScene();
Stage window = (Stage) ((Node) e.getSource()).getScene().getWindow();
window.setResizable(false);
window.setWidth(800);
window.setHeight(600);
window.setScene(seatMapScene);
window.show();
}
catch (IOException ex) {
ex.printStackTrace();
}
}
});
time.setPrefSize(100, 100);
time.setAlignment(Pos.CENTER);
time.setStyle("-fx-border-color: black");
time.setStyle("-fx-font: 22 arial;");
time.setStyle("-fx-text-fill: white");
time.setText(screeningList.get(j).getShowTime());
timesHolder.getChildren().add(time);
}
}
infoHolder.getChildren().add(timesHolder);
holder.getChildren().add(infoHolder);
}
}
}
The main class
public class MovieShowings{
private AnchorPane root;
public MovieShowings() {
try {
root = FXMLLoader.load(getClass().getResource("movieshowings.fxml"));
}
catch(IOException e){
e.printStackTrace();
}
}
public Scene getScene() {
Scene scene = new Scene(root,800,600);
return scene;
}
public AnchorPane getRoot() {
return root;
}
}
and the code that calls it after the user has logged in
if(DatabaseConnection.getInstance().login(Username.getText(), Password.getText())) {
MovieShowings films = new MovieShowings();
MovieShowingsController filmsController = new MovieShowingsController(films);
Scene movieShowings = films.getScene();
Stage window = (Stage) ((Node) e.getSource()).getScene().getWindow();
window.setScene(movieShowings);
window.show();
Any ideas as how to fix this?
Edit: The fx:id 'vbox' is not being accessed from the getRoot() method even though is has been injected into the FXML loader
The reason for this is that ScrollPane adds content, ScrollBars, ect. to the scene during the first layout pass when it's skin is created. This layout pass happens after the JavaFX application thread "regains control" (i.e. you're done with the event handler, Application.start method or similar way of having JavaFX execute your code).
Note that you're using your controller class in a pretty weird way. I recommend using one of the approaches described in the answers to this question to communicate with the controller: Passing Parameters JavaFX FXML
For example:
public class MovieShowings{
private AnchorPane root;
public MovieShowings() {
try {
FXMLLoader loader = new FXMLLoader(getClass().getResource("movieshowings.fxml"));
root = loader.load();
MovieShowingsController controller = loader.getController();
controller.initMovieShowings(this);
}
catch(IOException e){
e.printStackTrace();
}
}
...
}
public class MovieShowingsController {
...
public void initMovieShowings(MovieShowings showings) {
String date = "2019-04-15";
Date sqlDate = Date.valueOf(date);
System.out.println("\n");
System.out.println("***Screenings for " + date + "***");
filmList = new ArrayList();
screeningList = DatabaseConnection.getInstance().retrieveScreeningsForDay(sqlDate);
for (Screening screeningInstance : screeningList) {
if (!filmList.contains(screeningInstance.getFilmInfo())) {
filmList.add(screeningInstance.getFilmInfo());
}
System.out.println(screeningInstance.toString());
}
Collections.sort(screeningList);
this.showings = showings;
//populating FXML instance variable from loader
// use the injected field here
buildMovieShowings(vbox);
}
...
}
Since you don't actually use the MovieShowings object in your controller, the code could be simplified a bit by doing teh initialisation from a
#FXML
private void initialize()
method in the controller and remove every MovieShowings-related part from the controller code. This way you'd get rid of the necessity to pass it to the controller.
Using a ListView using custom cells could also be an option to display the movies...

BorderPane not updating despite links between FXML <-> Controller <-> Subclass of Application

Relevant Files: (apologies on any formatting, made many attempts to make it work)
If the files are not sufficient, the repository is here: https://github.com/TheeNinja/StockLookupTool
stock_lookup_tool_main.fxml
<BorderPane fx:id="borderPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.112" xmlns:fx="http://javafx.com/fxml/1" fx:controller="me.theeninja.stocklookuptool.gui.StockLookupToolApplicationController">
<top>
...
</top>
<left />
<center />
</BorderPane>
stock_information_center.fxml
<GridPane xmlns="http://javafx.com/javafx"
xmlns:fx="http://javafx.com/fxml"
fx:controller="me.theeninja.stocklookuptool.gui.selection.StockSearchSelectionController"
prefHeight="400.0" prefWidth="600.0"
fx:id="stockInformationCenter">
</GridPane>
favorite_stocks_sidebar.fxml
<VBox xmlns:fx="http://javafx.com/fxml/1" fx:controller="me.theeninja.stocklookuptool.gui.selection.StockSearchSelectionController" fx:id="verticalStockList">
...
</VBox>
StockLookupTool.java (Class with the start method)
public class StockLookupTool extends Application {
....
#Override
public void start(Stage stage) throws Exception {
...
FXMLLoader loader = new FXMLLoader();
loader.setLocation(getClass().getResource("/fxml/stock_lookup_tool_main.fxml"));
Parent root = loader.load();
Scene scene = new Scene(root, 250, 300);
stage.setTitle(APPLICATION_TITLE);
stage.setScene(scene);
stage.setFullScreen(true);
stage.show();
}
....
}
StockLookupToolApplicationController (controller for stock_lookup_tool_main.fxml)
public class StockLookupToolApplicationController {
...
#FXML public Label stockSearchLabel;
#FXML public Label newsLabel;
#FXML public Label settings;
#FXML public BorderPane borderPane;
#FXML public HBox topApplicationNavigation;
#FXML
public void handleStockSearchSelection() {
logger.log(Level.INFO, "Setting GUI View to Stock Search");
setView(StockSearchSelectionController.getInstance());
}
private void setView(Selection selection) {
borderPane.setLeft(selection.getLeft());
borderPane.setCenter(selection.getCenter());
borderPane.setRight(selection.getRight());
borderPane.setBottom(selection.getBottom());
}
}
StockSearchSelectionController.java (controller for both stock_information_center.fxml and favorite_stocks_sidebar.fxml)
public class StockSearchSelectionController implements Selection {
#FXML public Label favoriteStocksLabel;
#FXML public TextField addFavoriteStockInput;
#FXML public VBox verticalStockList;
#FXML public HBox addFavoriteStockInputContainer;
#FXML public GridPane stockInformationCenter;
#FXML
public void handleFavoriteStockInput(KeyEvent keyEvent) {
if (keyEvent.getCode() == KeyCode.ENTER) {
...
// makes visual changes to both stockInformationCenter AND verticalStockList, hence I need access to both fxml files (which is why this controls both).
}
}
#Override
public Node getLeft() {
return verticalStockList;
}
#Override
public Node getCenter() {
return stockInformationCenter;
}
}
More information:
The interface Selection has the methods getLeft() and getCenter() (among other irrelevant ones). Both of these returns Node. In stock_lookup_tool_main.fxml, in the top portion of the BorderPane I have a button (cut out in the provided snippet) that, when pressed, calls handleStockSearchSelection() (this method call indeed happens, I have verified it with a logger).
Now there is a controller, that controls both stock_information_center.fxml and favorite_stocks_sidebar.fxml. This controller implements Selection, and in turn, implements getLeft() and getCenter(). getLeft() returns the VBox variable
that correlates to favorite_stocks_sidebar.fxml, while getCenter() returns the GridPane variable that correlates to stock_information_center.fxml. When handleStockSearchSelection() is called, the left part of the borderPane object is set to the VBox, and the center is set to the GridPane. All these method calls/actions have been verified to occur. However, there is no visual change to the scene.
My question is: Why are these changes to borderPane not implemented visually in the scene? I have established a link between the scene <-> stock_lookup_tool_main.fxml through setting the loader's location. I have also established a link between stock_lookup_tool_main.fxml <-> its controller, hence they should share changes. I have modified the border pane in stock_lookup_tool_main.fxml in the controller by calling setLeft() and setCenter() on the variable (same name as the ID, borderPane). Yet, the scene visually does not change.

How to redirect System.out using different thread in JavaFX with FXML

I have multiple tabs and one of them is my console output. I am trying to redirect System.out/err to TextArea loggerPane in that console output Tab using JavaFX. My question is how can I do that in a different thread because while it's outputting I can't navigate to the console tab.
Main App:
public initRootLayout(){
FXMLoader loader = new FXMLLoader();
loader.setLocation(MainApp.class.getResource(RootLayout.fxml))
rootLayout = (BorderPane) loader.load();
scene = new Scene (rootLayout);
primaryStage.setScene(scene);
rootLayoutController = loader.getController();
rootLayoutController.setMainApp(this);
primaryStage.show();
}
I included the ConsoleController in RootController where I have all the tabs
#FXML private ConsoleController consoleController
RootLayoutFXML: I included the consoleFXML that uses its own controller
<Tab text="Console">
<content>
fx:include fx:id="myConsolePane" source="console.fxml"
</content>
</Tab>
ConsoleController
public class ConsoleController implements Initializable {
#FXML
private TextArea loggerPane;
public void appendText(String valueOf){
Platform.runLater(()-> loggerPane.appendText(valueOf))
}
#Override
public void initialize (URL ur, ResourceBundle rb){
OutputStream out = new OutputStream(){
#Override
public void write(int b) throws IOException{
appendText(String.valueOf((char)b));
}
};
System.setOut(out, true);
System.setErr(out, true);
}
Background Thread:
It's calling background class that interacts with a Rest API to
preform a function, sometime it outputs a long string as part of
the validation which I want to capture in the console tab.

JavaFx - TextField.setText() throwing nullpointerException

im trying to add some text to a textfield, but when i click the button it shows nullpointerexception , why is this happening?
MainWindowController.java
#FXML
public TextField konsumatoriPunetField = new TextField();
#FXML
private void initialize()
{
FXMLLoader loader5 = new FXMLLoader();
loader5.setLocation(getClass().getResource("ZgjedhKonsumatorinFXML.fxml"));
BorderPane border5 = new BorderPane();
border5 = loader5.load();
Scene scene5 = new Scene(border5);
zgjedhkonsumatorinstage.setScene(scene5);
zgjedhkonsumatorinstage.setTitle("Pit Stop");
zgjedhkonsumatorinstage.initModality(Modality.WINDOW_MODAL);
zgjedhkonsumatorinstage.initOwner(MainFXMLController.mainFXMLStage);
}
#FXML
public void zgjedhKonsumatorin()
{
zgjedhkonsumatorinstage.showAndWait();
}
MainWindowFXML.fxml
<TextField fx:id="konsumatoriPunetField" editable="false" onMouseClicked="#zgjedhKonsumatorin" promptText="Kliko per te zgjedhur" GridPane.columnIndex="1" GridPane.rowIndex="1" />
ZgjedhKonsumatorinController.java
#FXML
public void zgjedhKonsumatorin()
{
FXMLLoader loader = new FXMLLoader(getClass().getResource("MainWindowFXML.fxml"));
MainWindowController c = (MainWindowController) loader.getController();
c.konsumatoriPunetField.textProperty().setValue("ertani");
main.zgjedhkonsumatorinstage.close();
}
ZgjedhKonsumatorinFXML.fxml
<Button mnemonicParsing="false" onAction="#zgjedhKonsumatorin" prefWidth="150.0" text="Zgjedh Konsumatorin" />
Output:
Caused by: java.lang.NullPointerException
at main.ZgjedhKonsumatorinController.zgjedhKonsumatorin(ZgjedhKonsumatorinController.java:193)
... 102 more
p.s. this is the line 193 in ZgjedhKonsumatorinController (exception)
c.konsumatoriPunetField.textProperty().setValue("ertani");
The controller is created by the FXMLLoader when you load the FXML file (the controller class is specified by the FXML file, so this is the only time it could be created). So if you call loader.getController() before calling load(), the value returned will be null. Hence in your code c is null and you get a null pointer exception.
Note that it won't actually help to call loader.load() here. It would fix the null pointer exception, but of course you would load a new instance of the UI defined by the FXML file, and a new instance of the controller. Hence the text field whose text you are setting would not be the text field that is displayed, and nothing would happen.
Since you are using showAndWait() on the window you create, the easiest way to set the text is just to do it back in the MainWindowController, after the showAndWait() call completes. showAndWait() blocks execution until the window is closed, so the text field won't change until the window is closed.
First define a method in ZgjedhKonsumatorinController for retrieving the text:
public class ZgjedhKonsumatorinController {
#FXML
public void zgjedhKonsumatorin()
{
main.zgjedhkonsumatorinstage.close();
}
public String getText() {
// in real life you can get text from the controls in ZgjedhKonsumatorinFXML.fxml
return "ertani" ;
}
}
and now back in MainWindowController you can do:
public class MainWindowController {
#FXML
// Note: it is ALWAYS a mistake to initialize #FXML-injected fields.
// Just declare them and let the FXMLLoader initialize them
// (that is the whole point of #FXML)
private TextField konsumatoriPunetField ;
private ZgjedhKonsumatorinController zgjedhKonsumatorinController ;
#FXML
private void initialize()
{
FXMLLoader loader5 = new FXMLLoader();
loader5.setLocation(getClass().getResource("ZgjedhKonsumatorinFXML.fxml"));
BorderPane border5 = new BorderPane();
border5 = loader5.load();
zgjedhKonsumatorinController = loader.getController();
Scene scene5 = new Scene(border5);
zgjedhkonsumatorinstage.setScene(scene5);
zgjedhkonsumatorinstage.setTitle("Pit Stop");
zgjedhkonsumatorinstage.initModality(Modality.WINDOW_MODAL);
zgjedhkonsumatorinstage.initOwner(MainFXMLController.mainFXMLStage);
}
#FXML
public void zgjedhKonsumatorin()
{
zgjedhkonsumatorinstage.showAndWait();
konsumatoriPunetField.setText(zgjedhKonsumatorinController.getText());
}
}

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