Can't instantiate class fields in JavaFX project

Can't instantiate class fields in JavaFX project - java

So I'm trying to move from Swing to JavaFX and I just declare the start() and launch() methods without knowing how they work. But below code prints false and false to the console. However when I click the button in the GUI, built with Scene Builder, that executes myMethod(), this time it prints true. Why does it say that primaryStage isn't instantiated?
addition information:
I also made this class my Controller, for the same reason - it needs access to the Stage reference. The full version of Main, which I didn't post, implements Initializable if that matters.
As a bonus question I was wondering if I need the field of primaryStage to reference the Application Stage, which there would only be one of?, in myMethod().
public class Main extends Application {
private Stage primaryStage;
public void start(Stage primaryStage) {
this.primaryStage = primaryStage;
try {
Scene scene = new Scene(FXMLLoader.load(getClass().getResource("Sample.fxml")),600,400);
primaryStage.setScene(scene);
} catch(Exception e) {
e.printStackTrace();
}
primaryStage.show();
//both lines below print false; As they should.
System.out.println(this.primaryStage == null);
myMethod();
}
public static void main(String[] args) {
launch(args);
}
public void myMethod() {
System.out.println(primaryStage == null);
}
}
EDIT
placing this FXML document in the same folder as above class will let you run Main to see that the button does indeed print true.
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.AnchorPane?>
<HBox xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.Main">
<children>
<Button mnemonicParsing="false" onAction="#myMethod" text="Button" />
</children>
</HBox>

That is because the FXMLLoader will create new instance of application.Main class, in where the start() method is not invoked and thus private Stage primaryStage is null.
It is better to separate the main class and the controller for the FXML, and pass the primary stage later if it is necessary:
...
try
{
FXMLLoader loader = new FXMLLoader( getClass().getResource( "Sample.fxml" ) );
Scene scene = new Scene( loader.load(), 600, 400 );
( (MyController) loader.getController() ).setPrimaryStage(primaryStage);
primaryStage.setScene( scene );
}
catch ( Exception e )
{
e.printStackTrace();
}
...
where the MyController class can be as simple as:
public class MyController {
private Stage primaryStage;
public void setPrimaryStage(Stage primaryStage) {
this.primaryStage = primaryStage;
}
}
but also can implement Initializable interface. Refer to Introduction to FXML :: Controllers.
Also note that you can get the scene and its stage from any node that is part of that constructed scene graph (i.e. a stage that is shown) by:
Scene scene = anynode.getScene();
Stage primaryStage = (Stage) anynode.getScene().getWindow();
Of course, for the secondary stages created by you the getWindow() will return that stage and not the primary stage.

There is no need at all to jump through any of these hoops to get access to the window. You can just call getScene().getWindow() on any node to get the window in which it is displayed (and of course you can just inject any node into your controller in the usual way).
Don't use the Application subclass as the controller class: you will have (at least) two different instances (one created by the launch() method, because it's the Application subclass, and one created by the FXMLLoader, because it's the controller class). Different fields will be initialized in the different instances.
Create a controller class, and inject at least one node into it:
public class Controller {
#FXML
private Parent root ;
#FXML
private void myMethod() {
Window window = root.getScene().getStage();
// assuming you are running as a standalone application, the window
// will actually be a Stage instance.
window.hide(); // for example...
}
}
Use this as your controller class and inject the node into it:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.AnchorPane?>
<HBox xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.Controller" fx:id="root">
<children>
<Button mnemonicParsing="false" onAction="#myMethod" text="Button" />
</children>
</HBox>

Related

fxml view won't update: How can I get my controller to update my 1st view after processing a call from my 2nd view? [duplicate]

How can I pass parameters to a secondary window in javafx? Is there a way to communicate with the corresponding controller?
For example:
The user chooses a customer from a TableView and a new window is opened, showing the customer's info.
Stage newStage = new Stage();
try
{
AnchorPane page = (AnchorPane) FXMLLoader.load(HectorGestion.class.getResource(fxmlResource));
Scene scene = new Scene(page);
newStage.setScene(scene);
newStage.setTitle(windowTitle);
newStage.setResizable(isResizable);
if(showRightAway)
{
newStage.show();
}
}
newStage would be the new window. The problem is, I can't find a way to tell the controller where to look for the customer's info (by passing the id as parameter).
Any ideas?

Using MVC
Most of this answer focuses on a direct call to pass a parameter from a calling class to the controller.
If instead, you want to decouple the caller and controller and use a more general architecture involving a model class with settable and listenable properties to achieve inter-controller communication, see the following basic overview:
Applying MVC With JavaFx
Recommended Approach
This answer enumerates different mechanisms for passing parameters to FXML controllers.
For small applications I highly recommend passing parameters directly from the caller to the controller - it's simple, straightforward and requires no extra frameworks.
For larger, more complicated applications, it would be worthwhile investigating if you want to use Dependency Injection or Event Bus mechanisms within your application.
Passing Parameters Directly From the Caller to the Controller
Pass custom data to an FXML controller by retrieving the controller from the FXML loader instance and calling a method on the controller to initialize it with the required data values.
Something like the following code:
public Stage showCustomerDialog(Customer customer) {
FXMLLoader loader = new FXMLLoader(
getClass().getResource(
"customerDialog.fxml"
)
);
Stage stage = new Stage(StageStyle.DECORATED);
stage.setScene(
new Scene(loader.load())
);
CustomerDialogController controller = loader.getController();
controller.initData(customer);
stage.show();
return stage;
}
...
class CustomerDialogController {
#FXML private Label customerName;
void initialize() {}
void initData(Customer customer) {
customerName.setText(customer.getName());
}
}
A new FXMLLoader is constructed as shown in the sample code i.e. new FXMLLoader(location). The location is a URL and you can generate such a URL from an FXML resource by:
new FXMLLoader(getClass().getResource("sample.fxml"));
Be careful NOT to use a static load function on the FXMLLoader, or you will not be able to get your controller from your loader instance.
FXMLLoader instances themselves never know anything about domain objects. You do not directly pass application specific domain objects into the FXMLLoader constructor, instead you:
Construct an FXMLLoader based upon fxml markup at a specified location
Get a controller from the FXMLLoader instance.
Invoke methods on the retrieved controller to provide the controller with references to the domain objects.
This blog (by another writer) provides an alternate, but similar, example.
Setting a Controller on the FXMLLoader
CustomerDialogController dialogController =
new CustomerDialogController(param1, param2);
FXMLLoader loader = new FXMLLoader(
getClass().getResource(
"customerDialog.fxml"
)
);
loader.setController(dialogController);
Pane mainPane = loader.load();
You can construct a new controller in code, passing any parameters you want from your caller into the controller constructor. Once you have constructed a controller, you can set it on an FXMLLoader instance before you invoke the load() instance method.
To set a controller on a loader (in JavaFX 2.x) you CANNOT also define a fx:controller attribute in your fxml file.
Due to the limitation on the fx:controller definition in FXML, I personally prefer getting the controller from the FXMLLoader rather than setting the controller into the FXMLLoader.
Having the Controller Retrieve Parameters from an External Static Method
This method is exemplified by Sergey's answer to Javafx 2.0 How-to Application.getParameters() in a Controller.java file.
Use Dependency Injection
FXMLLoader supports dependency injection systems like Guice, Spring or Java EE CDI by allowing you to set a custom controller factory on the FXMLLoader. This provides a callback that you can use to create the controller instance with dependent values injected by the respective dependency injection system.
An example of JavaFX application and controller dependency injection with Spring is provided in the answer to:
Adding Spring Dependency Injection in JavaFX (JPA Repo, Service)
A really nice, clean dependency injection approach is exemplified by the afterburner.fx framework with a sample air-hacks application that uses it. afterburner.fx relies on JEE6 javax.inject to perform the dependency injection.
Use an Event Bus
Greg Brown, the original FXML specification creator and implementor, often suggests considering use of an event bus, such as the Guava EventBus, for communication between FXML instantiated controllers and other application logic.
The EventBus is a simple but powerful publish/subscribe API with annotations that allows POJOs to communicate with each other anywhere in a JVM without having to refer to each other.
Follow-up Q&A
on first method, why do you return Stage? The method can be void as well because you already giving the command show(); just before return stage;. How do you plan usage by returning the Stage
It is a functional solution to a problem. A stage is returned from the showCustomerDialog function so that a reference to it can be stored by an external class which may wish to do something, such as hide the stage based on a button click in the main window, at a later time. An alternate, object-oriented solution could encapsulate the functionality and stage reference inside a CustomerDialog object or have a CustomerDialog extend Stage. A full example for an object-oriented interface to a custom dialog encapsulating FXML, controller and model data is beyond the scope of this answer, but may make a worthwhile blog post for anybody inclined to create one.
Additional information supplied by StackOverflow user named #dzim
Example for Spring Boot Dependency Injection
The question of how to do it "The Spring Boot Way", there was a discussion about JavaFX 2, which I anserwered in the attached permalink.
The approach is still valid and tested in March 2016, on Spring Boot v1.3.3.RELEASE:
https://stackoverflow.com/a/36310391/1281217
Sometimes, you might want to pass results back to the caller, in which case you can check out the answer to the related question:
JavaFX FXML Parameter passing from Controller A to B and back

I realize this is a very old post and has some great answers already,
but I wanted to make a simple MCVE to demonstrate one such approach and allow new coders a way to quickly see the concept in action.
In this example, we will use 5 files:
Main.java - Simply used to start the application and call the first controller.
Controller1.java - The controller for the first FXML layout.
Controller2.java - The controller for the second FXML layout.
Layout1.fxml - The FXML layout for the first scene.
Layout2.fxml - The FXML layout for the second scene.
All files are listed in their entirety at the bottom of this post.
The Goal: To demonstrate passing values from Controller1 to Controller2 and vice versa.
The Program Flow:
The first scene contains a TextField, a Button, and a Label. When the Button is clicked, the second window is loaded and displayed, including the text entered in the TextField.
Within the second scene, there is also a TextField, a Button, and a Label. The Label will display the text entered in the TextField on the first scene.
Upon entering text in the second scene's TextField and clicking its Button, the first scene's Label is updated to show the entered text.
This is a very simple demonstration and could surely stand for some improvement, but should make the concept very clear.
The code itself is also commented with some details of what is happening and how.
THE CODE
Main.java:
import javafx.application.Application;
import javafx.stage.Stage;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
// Create the first controller, which loads Layout1.fxml within its own constructor
Controller1 controller1 = new Controller1();
// Show the new stage
controller1.showStage();
}
}
Controller1.java:
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.stage.Stage;
import java.io.IOException;
public class Controller1 {
// Holds this controller's Stage
private final Stage thisStage;
// Define the nodes from the Layout1.fxml file. This allows them to be referenced within the controller
#FXML
private TextField txtToSecondController;
#FXML
private Button btnOpenLayout2;
#FXML
private Label lblFromController2;
public Controller1() {
// Create the new stage
thisStage = new Stage();
// Load the FXML file
try {
FXMLLoader loader = new FXMLLoader(getClass().getResource("Layout1.fxml"));
// Set this class as the controller
loader.setController(this);
// Load the scene
thisStage.setScene(new Scene(loader.load()));
// Setup the window/stage
thisStage.setTitle("Passing Controllers Example - Layout1");
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* Show the stage that was loaded in the constructor
*/
public void showStage() {
thisStage.showAndWait();
}
/**
* The initialize() method allows you set setup your scene, adding actions, configuring nodes, etc.
*/
#FXML
private void initialize() {
// Add an action for the "Open Layout2" button
btnOpenLayout2.setOnAction(event -> openLayout2());
}
/**
* Performs the action of loading and showing Layout2
*/
private void openLayout2() {
// Create the second controller, which loads its own FXML file. We pass a reference to this controller
// using the keyword [this]; that allows the second controller to access the methods contained in here.
Controller2 controller2 = new Controller2(this);
// Show the new stage/window
controller2.showStage();
}
/**
* Returns the text entered into txtToSecondController. This allows other controllers/classes to view that data.
*/
public String getEnteredText() {
return txtToSecondController.getText();
}
/**
* Allows other controllers to set the text of this layout's Label
*/
public void setTextFromController2(String text) {
lblFromController2.setText(text);
}
}
Controller2.java:
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.stage.Stage;
import java.io.IOException;
public class Controller2 {
// Holds this controller's Stage
private Stage thisStage;
// Will hold a reference to the first controller, allowing us to access the methods found there.
private final Controller1 controller1;
// Add references to the controls in Layout2.fxml
#FXML
private Label lblFromController1;
#FXML
private TextField txtToFirstController;
#FXML
private Button btnSetLayout1Text;
public Controller2(Controller1 controller1) {
// We received the first controller, now let's make it usable throughout this controller.
this.controller1 = controller1;
// Create the new stage
thisStage = new Stage();
// Load the FXML file
try {
FXMLLoader loader = new FXMLLoader(getClass().getResource("Layout2.fxml"));
// Set this class as the controller
loader.setController(this);
// Load the scene
thisStage.setScene(new Scene(loader.load()));
// Setup the window/stage
thisStage.setTitle("Passing Controllers Example - Layout2");
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* Show the stage that was loaded in the constructor
*/
public void showStage() {
thisStage.showAndWait();
}
#FXML
private void initialize() {
// Set the label to whatever the text entered on Layout1 is
lblFromController1.setText(controller1.getEnteredText());
// Set the action for the button
btnSetLayout1Text.setOnAction(event -> setTextOnLayout1());
}
/**
* Calls the "setTextFromController2()" method on the first controller to update its Label
*/
private void setTextOnLayout1() {
controller1.setTextFromController2(txtToFirstController.getText());
}
}
Layout1.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<AnchorPane xmlns="http://javafx.com/javafx/9.0.1" xmlns:fx="http://javafx.com/fxml/1">
<VBox alignment="CENTER" spacing="10.0">
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0"/>
</padding>
<Label style="-fx-font-weight: bold;" text="This is Layout1!"/>
<HBox alignment="CENTER_LEFT" spacing="10.0">
<Label text="Enter Text:"/>
<TextField fx:id="txtToSecondController"/>
<Button fx:id="btnOpenLayout2" mnemonicParsing="false" text="Open Layout2"/>
</HBox>
<VBox alignment="CENTER">
<Label text="Text From Controller2:"/>
<Label fx:id="lblFromController2" text="Nothing Yet!"/>
</VBox>
</VBox>
</AnchorPane>
Layout2.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<AnchorPane xmlns="http://javafx.com/javafx/9.0.1" xmlns:fx="http://javafx.com/fxml/1">
<VBox alignment="CENTER" spacing="10.0">
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0"/>
</padding>
<Label style="-fx-font-weight: bold;" text="Welcome to Layout 2!"/>
<VBox alignment="CENTER">
<Label text="Text From Controller1:"/>
<Label fx:id="lblFromController1" text="Nothing Yet!"/>
</VBox>
<HBox alignment="CENTER_LEFT" spacing="10.0">
<Label text="Enter Text:"/>
<TextField fx:id="txtToFirstController"/>
<Button fx:id="btnSetLayout1Text" mnemonicParsing="false" text="Set Text on Layout1"/>
</HBox>
</VBox>
</AnchorPane>

Here is an example for passing parameters to a fxml document through namespace.
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.layout.VBox?>
<VBox xmlns="http://javafx.com/javafx/null" xmlns:fx="http://javafx.com/fxml/1">
<BorderPane>
<center>
<Label text="$labelText"/>
</center>
</BorderPane>
</VBox>
Define value External Text for namespace variable labelText:
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import java.io.IOException;
public class NamespaceParameterExampleApplication extends Application {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) throws IOException {
final FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("namespace-parameter-example.fxml"));
fxmlLoader.getNamespace()
.put("labelText", "External Text");
final Parent root = fxmlLoader.load();
primaryStage.setTitle("Namespace Parameter Example");
primaryStage.setScene(new Scene(root, 400, 400));
primaryStage.show();
}
}

javafx.scene.Node class has a pair of methods
setUserData(Object)
and
Object getUserData()
Which you could use to add your info to the Node.
So, you can call page.setUserData(info);
And controller can check, if info is set. Also, you could use ObjectProperty for back-forward data transfering, if needed.
Observe a documentation here:
http://docs.oracle.com/javafx/2/api/javafx/fxml/doc-files/introduction_to_fxml.html
Before the phrase "In the first version, the handleButtonAction() is tagged with #FXML to allow markup defined in the controller's document to invoke it. In the second example, the button field is annotated to allow the loader to set its value. The initialize() method is similarly annotated."
So, you need to associate a controller with a node, and set a user data to the node.

This WORKS ..
Remember first time you print the passing value you will get null,
You can use it after your windows loaded , same for everything you want to code for any other component.
First Controller
try {
Stage st = new Stage();
FXMLLoader loader = new FXMLLoader(getClass().getResource("/com/inty360/free/form/MainOnline.fxml"));
Parent sceneMain = loader.load();
MainOnlineController controller = loader.<MainOnlineController>getController();
controller.initVariable(99L);
Scene scene = new Scene(sceneMain);
st.setScene(scene);
st.setMaximized(true);
st.setTitle("My App");
st.show();
} catch (IOException ex) {
Logger.getLogger(LoginController.class.getName()).log(Level.SEVERE, null, ex);
}
Another Controller
public void initVariable(Long id_usuario){
this.id_usuario = id_usuario;
label_usuario_nombre.setText(id_usuario.toString());
}

You have to create one Context Class.
public class Context {
private final static Context instance = new Context();
public static Context getInstance() {
return instance;
}
private Connection con;
public void setConnection(Connection con)
{
this.con=con;
}
public Connection getConnection() {
return con;
}
private TabRoughController tabRough;
public void setTabRough(TabRoughController tabRough) {
this.tabRough=tabRough;
}
public TabRoughController getTabRough() {
return tabRough;
}
}
You have to just set instance of controller in initialization using
Context.getInstance().setTabRough(this);
and you can use it from your whole application just using
TabRoughController cont=Context.getInstance().getTabRough();
Now you can pass parameter to any controller from whole application.

Yes you can.
You need to add in the first controller:
YourController controller = loader.getController();
controller.setclient(client);
Then in the second one declare a client, then at the bottom of your controller:
public void setclien(Client c) {
this.client = c;
}

Here is an example for using a controller injected by Guice.
/**
* Loads a FXML file and injects its controller from the given Guice {#code Provider}
*/
public abstract class GuiceFxmlLoader {
public GuiceFxmlLoader(Stage stage, Provider<?> provider) {
mStage = Objects.requireNonNull(stage);
mProvider = Objects.requireNonNull(provider);
}
/**
* #return the FXML file name
*/
public abstract String getFileName();
/**
* Load FXML, set its controller with given {#code Provider}, and add it to {#code Stage}.
*/
public void loadView() {
try {
FXMLLoader loader = new FXMLLoader(getClass().getClassLoader().getResource(getFileName()));
loader.setControllerFactory(p -> mProvider.get());
Node view = loader.load();
setViewInStage(view);
}
catch (IOException ex) {
LOGGER.error("Failed to load FXML: " + getFileName(), ex);
}
}
private void setViewInStage(Node view) {
BorderPane pane = (BorderPane)mStage.getScene().getRoot();
pane.setCenter(view);
}
private static final Logger LOGGER = Logger.getLogger(GuiceFxmlLoader.class);
private final Stage mStage;
private final Provider<?> mProvider;
}
Here is a concrete implementation of the loader:
public class ConcreteViewLoader extends GuiceFxmlLoader {
#Inject
public ConcreteViewLoader(Stage stage, Provider<MyController> provider) {
super(stage, provider);
}
#Override
public String getFileName() {
return "my_view.fxml";
}
}
Note this example loads the view into the center of a BoarderPane that is the root of the Scene in the Stage. This is irrelevant to the example (implementation detail of my specific use case) but decided to leave it in as some may find it useful.

You can decide to use a public observable list to store public data, or just create a public setter method to store data and retrieve from the corresponding controller

Why answer a 6 year old question ?
One the most fundamental concepts working with any programming language is how to navigate from one (window, form or page) to another. Also while doing this navigation the developer often wants to pass data from one (window, form or page) and display or use the data passed
While most of the answers here provide good to excellent examples how to accomplish this we thought we would kick it up a notch or two or three
We said three because we will navigate between three (window, form or page) and use the concept of static variables to pass data around the (window, form or page)
We will also include some decision making code while we navigate
public class Start extends Application {
#Override
public void start(Stage stage) throws Exception {
// This is MAIN Class which runs first
Parent root = FXMLLoader.load(getClass().getResource("start.fxml"));
Scene scene = new Scene(root);
stage.setScene(scene);
stage.setResizable(false);// This sets the value for all stages
stage.setTitle("Start Page");
stage.show();
stage.sizeToScene();
}
public static void main(String[] args) {
launch(args);
}
}
Start Controller
public class startController implements Initializable {
#FXML Pane startPane,pageonePane;
#FXML Button btnPageOne;
#FXML TextField txtStartValue;
public Stage stage;
public static int intSETonStartController;
String strSETonStartController;
#FXML
private void toPageOne() throws IOException{
strSETonStartController = txtStartValue.getText().trim();
// yourString != null && yourString.trim().length() > 0
// int L = testText.length();
// if(L == 0){
// System.out.println("LENGTH IS "+L);
// return;
// }
/* if (testText.matches("[1-2]") && !testText.matches("^\\s*$"))
Second Match is regex for White Space NOT TESTED !
*/
String testText = txtStartValue.getText().trim();
// NOTICE IF YOU REMOVE THE * CHARACTER FROM "[1-2]*"
// NO NEED TO CHECK LENGTH it also permited 12 or 11 as valid entry
// =================================================================
if (testText.matches("[1-2]")) {
intSETonStartController = Integer.parseInt(strSETonStartController);
}else{
txtStartValue.setText("Enter 1 OR 2");
return;
}
System.out.println("You Entered = "+intSETonStartController);
stage = (Stage)startPane.getScene().getWindow();// pane you are ON
pageonePane = FXMLLoader.load(getClass().getResource("pageone.fxml"));// pane you are GOING TO
Scene scene = new Scene(pageonePane);// pane you are GOING TO
stage.setScene(scene);
stage.setTitle("Page One");
stage.show();
stage.sizeToScene();
stage.centerOnScreen();
}
private void doGET(){
// Why this testing ?
// strSENTbackFROMPageoneController is null because it is set on Pageone
// =====================================================================
txtStartValue.setText(strSENTbackFROMPageoneController);
if(intSETonStartController == 1){
txtStartValue.setText(str);
}
System.out.println("== doGET WAS RUN ==");
if(txtStartValue.getText() == null){
txtStartValue.setText("");
}
}
#Override
public void initialize(URL url, ResourceBundle rb) {
// This Method runs every time startController is LOADED
doGET();
}
}
Page One Controller
public class PageoneController implements Initializable {
#FXML Pane startPane,pageonePane,pagetwoPane;
#FXML Button btnOne,btnTwo;
#FXML TextField txtPageOneValue;
public static String strSENTbackFROMPageoneController;
public Stage stage;
#FXML
private void onBTNONE() throws IOException{
stage = (Stage)pageonePane.getScene().getWindow();// pane you are ON
pagetwoPane = FXMLLoader.load(getClass().getResource("pagetwo.fxml"));// pane you are GOING TO
Scene scene = new Scene(pagetwoPane);// pane you are GOING TO
stage.setScene(scene);
stage.setTitle("Page Two");
stage.show();
stage.sizeToScene();
stage.centerOnScreen();
}
#FXML
private void onBTNTWO() throws IOException{
if(intSETonStartController == 2){
Alert alert = new Alert(AlertType.CONFIRMATION);
alert.setTitle("Alert");
alert.setHeaderText("YES to change Text Sent Back");
alert.setResizable(false);
alert.setContentText("Select YES to send 'Alert YES Pressed' Text Back\n"
+ "\nSelect CANCEL send no Text Back\r");// NOTE this is a Carriage return\r
ButtonType buttonTypeYes = new ButtonType("YES");
ButtonType buttonTypeCancel = new ButtonType("CANCEL", ButtonData.CANCEL_CLOSE);
alert.getButtonTypes().setAll(buttonTypeYes, buttonTypeCancel);
Optional<ButtonType> result = alert.showAndWait();
if (result.get() == buttonTypeYes){
txtPageOneValue.setText("Alert YES Pressed");
} else {
System.out.println("canceled");
txtPageOneValue.setText("");
onBack();// Optional
}
}
}
#FXML
private void onBack() throws IOException{
strSENTbackFROMPageoneController = txtPageOneValue.getText();
System.out.println("Text Returned = "+strSENTbackFROMPageoneController);
stage = (Stage)pageonePane.getScene().getWindow();
startPane = FXMLLoader.load(getClass().getResource("start.fxml"));
Scene scene = new Scene(startPane);
stage.setScene(scene);
stage.setTitle("Start Page");
stage.show();
stage.sizeToScene();
stage.centerOnScreen();
}
private void doTEST(){
String fromSTART = String.valueOf(intSETonStartController);
txtPageOneValue.setText("SENT "+fromSTART);
if(intSETonStartController == 1){
btnOne.setVisible(true);
btnTwo.setVisible(false);
System.out.println("INTEGER Value Entered = "+intSETonStartController);
}else{
btnOne.setVisible(false);
btnTwo.setVisible(true);
System.out.println("INTEGER Value Entered = "+intSETonStartController);
}
}
#Override
public void initialize(URL url, ResourceBundle rb) {
doTEST();
}
}
Page Two Controller
public class PagetwoController implements Initializable {
#FXML Pane startPane,pagetwoPane;
public Stage stage;
public static String str;
#FXML
private void toStart() throws IOException{
str = "You ON Page Two";
stage = (Stage)pagetwoPane.getScene().getWindow();// pane you are ON
startPane = FXMLLoader.load(getClass().getResource("start.fxml"));// pane you are GOING TO
Scene scene = new Scene(startPane);// pane you are GOING TO
stage.setScene(scene);
stage.setTitle("Start Page");
stage.show();
stage.sizeToScene();
stage.centerOnScreen();
}
#Override
public void initialize(URL url, ResourceBundle rb) {
}
}
Below are all the FXML files
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>
<AnchorPane id="AnchorPane" fx:id="pagetwoPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1" fx:controller="atwopage.PagetwoController">
<children>
<Button layoutX="227.0" layoutY="62.0" mnemonicParsing="false" onAction="#toStart" text="To Start Page">
<font>
<Font name="System Bold" size="18.0" />
</font>
</Button>
</children>
</AnchorPane>
<?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 id="AnchorPane" fx:id="startPane" prefHeight="200.0" prefWidth="400.0" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1" fx:controller="atwopage.startController">
<children>
<Label focusTraversable="false" layoutX="115.0" layoutY="47.0" text="This is the Start Pane">
<font>
<Font size="18.0" />
</font>
</Label>
<Button fx:id="btnPageOne" focusTraversable="false" layoutX="137.0" layoutY="100.0" mnemonicParsing="false" onAction="#toPageOne" text="To Page One">
<font>
<Font size="18.0" />
</font>
</Button>
<Label focusTraversable="false" layoutX="26.0" layoutY="150.0" text="Enter 1 OR 2">
<font>
<Font size="18.0" />
</font>
</Label>
<TextField fx:id="txtStartValue" layoutX="137.0" layoutY="148.0" prefHeight="28.0" prefWidth="150.0" />
</children>
</AnchorPane>
<?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 id="AnchorPane" fx:id="pageonePane" prefHeight="200.0" prefWidth="400.0" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1" fx:controller="atwopage.PageoneController">
<children>
<Label focusTraversable="false" layoutX="111.0" layoutY="35.0" text="This is Page One Pane">
<font>
<Font size="18.0" />
</font>
</Label>
<Button focusTraversable="false" layoutX="167.0" layoutY="97.0" mnemonicParsing="false" onAction="#onBack" text="BACK">
<font>
<Font size="18.0" />
</font></Button>
<Button fx:id="btnOne" focusTraversable="false" layoutX="19.0" layoutY="97.0" mnemonicParsing="false" onAction="#onBTNONE" text="Button One" visible="false">
<font>
<Font size="18.0" />
</font>
</Button>
<Button fx:id="btnTwo" focusTraversable="false" layoutX="267.0" layoutY="97.0" mnemonicParsing="false" onAction="#onBTNTWO" text="Button Two">
<font>
<Font size="18.0" />
</font>
</Button>
<Label focusTraversable="false" layoutX="19.0" layoutY="152.0" text="Send Anything BACK">
<font>
<Font size="18.0" />
</font>
</Label>
<TextField fx:id="txtPageOneValue" layoutX="195.0" layoutY="150.0" prefHeight="28.0" prefWidth="150.0" />
</children>
</AnchorPane>

javafx make new label on another fxml on button clicked

I want to create new label in another fxml when a button is clicked. I used the following code but the following exception is thrown
java.lang.RuntimeException:
java.lang.reflect.InvocationTargetException
The code:
Controller.java
public class Controller {
public AnchorPane anchorPane;
public void OpenSecond() throws Exception{
Stage primaryStage = new Stage();
Parent root = FXMLLoader.load(getClass().getResource("sample1.fxml"));
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(root, 300, 275));
primaryStage.show();
}
public void AddLabe(){
Label label = new Label("Label");
anchorPane.getChildren().add(label);
}
}
second.java
public class Second {
public void AddLiabel()
{
Controller controller = new Controller();
controller.AddLabe();
}
}
I am using IntelliJ IDEA and Scene builder

You should be getting this exception because Java couldn't find the specified file or it is empty. Search for
Caused by: javafx.fxml.LoadException:
in the exception.
Adding the "sample1.fxml" and initializing it with a pane should fix the problem.
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.Pane?>
<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="275.0" prefWidth="300.0" xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1" />

Most probably you miss annotation for anchorPane and JavaFX didn't initialize it. Try next:
#FXML
public AnchorPane anchorPane;
and make sure anchorPane is listed in your FXML file.

JavaFX - How to send a variable from a controller to the Main class?

----Revised draft----
I've been trying to create a game using JavaFX. In the game, a player sees a menu page at first("play game" ,"options","exit", etc), and he/she clicks the "OnlineGame" button to start a game.
And now I've already had a menu (created with fxml) and its controller.
<!-- MainMenu.fxml -->
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.media.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.text.*?>
<?import javafx.scene.effect.*?>
<?import java.lang.*?>
<?import javafx.scene.image.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="MainMenuController">
<children>
<Button fx:id="OnlineGame" layoutX="55.0" layoutY="157.0" mnemonicParsing="false" onAction="#OnlineGame" opacity="0.6" prefHeight="51.0" prefWidth="229.0" text="Play Online Game" textFill="#2067a1">
<font>
<Font size="21.0" />
</font>
</Button>
</children>
</AnchorPane>
The controller:
import *****;
//MainMenuController.java
public class MainMenuController{
#FXML private Button OnlineGame;
#FXML protected void OnlineGame(ActionEvent event) throws IOException{
//start the game
}
}
The menu is initialized in Main.start and it works well.
import *****;
public class Main extends Application {
public void start(Stage Stage) {
try {
Parent root = FXMLLoader.load(getClass().getResource("MainMenu.fxml"));
Scene scene = new Scene(root,730,439); //set SceneSize
Stage.setScene(scene);
Stage.show();
//call three methods to start a game
prepareGame();
addHandlers(scene);
startGame();
} catch(Exception e) {
e.printStackTrace();
}
}
private void prepareGame(){**********}
private void addHandlers(Scene scene){***********}
private void startGame(){****}
public static void main(String[] args) {
launch(args);
}
However, I also have some methods in Main.start to initialize a game.(prepareGame(); addHandlers(scene); startGame();). As you see, I also need to put them after stage.show;. So now the problem is that when I run my program, those three methods runs immediately (before I click my "OnlineGame" button in the menu!).
So are there any ways to achieve my goal(i.e. a player sees the game page after clicking "OnlineGame")?
PS: I simplified my code to make my question short(although it's still long :-D). I'm not a native speaker so if my words are confusing, please let me know so that I can explain it again. What's more, I'd like to post more details if necessary.
Thanks in advance!

Move all that logic to the controller: it has no place in the Application class.
If you want those three method to only be invoked when the button is pressed, then the obvious thing to do is to invoke them from the button's handler method:
public class MainMenuController {
#FXML
private Button onlineGame ;
#FXML
private void onlineGame(ActionEvent event) {
// button can't be pressed until it is in a scene, so getScene()
// here cannot return null:
addHandlers(game.getScene());
prepareGame();
startGame();
}
// ...
}
(Note that I changed the field and some method names so that they conform to standard Java naming conventions. You will need to change the FXML file to match these names.)

JavaFX: LoadException resolving onAction for event handler of a button [duplicate]

This question already has an answer here:
javafx 8 compatibility issues - FXML static fields
(1 answer)
Closed 5 years ago.
I am new to JavaFX. Trying to follow a tutorial to generate a scene and associate eventhandler with a button.
I created a Main.FXML and edited in SceneBuilder. Since I added SceneBuilder's path in my IDE, it is able to detect my main controller. I wrote a function to generate random number.
public class MainController {
public static void generateRandom(ActionEvent event) {
Random rand = new Random();
int myrand = rand.nextInt(500) + 1;
System.out.print(Integer.toString(myrand));
}
}
In scenebuilder, it detects this method in controller which can be easily added as eventhandler for OnAction of the button. Main.FXML is updated after the operations.
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane prefHeight="300" prefWidth="500" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8.0.111" fx:controller="application.MainController">
<children>
<Button layoutX="204.0" layoutY="204.0" mnemonicParsing="false" onAction="#generateRandom" text="Button" />
<Label layoutX="138.0" layoutY="36.0" prefHeight="144.0" prefWidth="210.0" />
</children>
</AnchorPane>
My main application class is as below:
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws IOException {
Parent root = FXMLLoader.load(getClass().getResource("/application/Main.fxml"));
Scene scene = new Scene(root,400,400);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setTitle("My Title");
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
When I run the app, I got error:
javafx.fxml.LoadException: Error resolving onAction='#generateRandom',
either the event handler is not in the Namespace or there is an error
in the script.
/C:/Users/Oscar/Workspace/Sunoco/bin/application/Main.fxml:10
Error resolving “onAction” while loading FXML suggests it may have to do with wrong import for ActionEvent which is not the case. Plus everything is set up automatically using SceneBuilder and Eclipse. So why am I getting this error?

I think the problem will be solved if you use an #FXML annotation on the eventMethod. Besides, try not to make methods static in the controller, as it may be confusing/misleading. If you need that method to be accesible from elsewhere, consider declaring it in a separate (utility like) class.

Why children are null ? JavaFX

I have a small code of javaFX.
I want to draw in canvas but I have some problem of beginner I really don't understand well javaFX.
This is my Main.java
package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application {
Controller controller;
#Override
public void start(Stage primaryStage) throws Exception{
controller= new Controller();
controller.Pane = FXMLLoader.load(getClass().getResource("sample.fxml"));
System.out.printf("kk"+controller.canvas.isResizable());
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(controller.Pane, controller.Pane.getPrefWidth(), controller.Pane.getPrefHeight()));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
this is sample.FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.canvas.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<AnchorPane fx:id="Pane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="284.0" prefWidth="484.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
<children>
<Canvas fx:id="canvas" height="267.0" layoutX="13.0" layoutY="9.0" width="459.0" AnchorPane.bottomAnchor="8.0" AnchorPane.leftAnchor="13.0" AnchorPane.rightAnchor="12.0" AnchorPane.topAnchor="9.0" />
</children>
</AnchorPane>
For the controller.java there is only canvas and pane declaration.
My question :
Pane is the parent and canvas is the children after doing FXMLloader.load etc, pane is not null but the children are null in the method start (outside like an event of button the children aren't null) why is children null?
To make the canvas resizable there is no method to do such thing, the only solution is to extends from Canvas and #Override method isResizable make it true. But Canvas I get it from FXML if I do
Canvas MyCanvas= new CanvasResizable();
this dosen't work I don't know why.
is there a way like android to make for example canvas=(Canvas) findbyid(FXML.id.canvas); (something similar)
and my last question how can we change the color of canvas there is no method to do that.
I'm sorry if my question is already asked by a diffirent why, I searched so much in google there is a lack of documentation of javaFX.

FXML controller should not be created directly. It will be initialized for you by FXMLLoader:
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception{
FXMLLoader loader = new FXMLLoader(getClass().getResource("sample.fxml"));
Pane root = loader.load(); // controller was initialized
controller = loader.getController();
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(root, root.getPrefWidth(), root.getPrefHeight()));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
You can find more details in Oracle tutorials: http://docs.oracle.com/javafx/2/fxml_get_started/fxml_tutorial_intermediate.htm#CACFEHBI

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Can't instantiate class fields in JavaFX project - java

Related

fxml view won't update: How can I get my controller to update my 1st view after processing a call from my 2nd view? [duplicate]

javafx make new label on another fxml on button clicked

JavaFX - How to send a variable from a controller to the Main class?

JavaFX: LoadException resolving onAction for event handler of a button [duplicate]

Why children are null ? JavaFX

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