Trying to acquaint myself with JavaFX I ran into the following problem:
I used Scene Builder to generate an FXML with my controller class specified as fx:controller="application.MainController" and I used the sample code generated by Scene Builder to create the MainController class in the according package.
Now although I'm not seeing any error messages apparently the initialize() method is never called after loading the FXML (tried Breakpoints and System.out.println). What am I missing?
Related
Ever since I manually set my Controllers the corresponding views don't seem to recognise my controllers. None of the view elements are recognised by my controllers and none of my Controller methods are recognised by their views. When I hover over the onaction='#...eventHandler' in my views it says there is no controller specified for the top level element.
However, I have set my Controllers (this is the main Controller and then there is another controller set somewhere else for a pop up window):
FXMLLoader loader = new FXMLLoader(getClass().getResource("foodDiaryView.fxml"));
FoodDiary foodDiary = new FoodDiary();
FoodDiaryController controller = new FoodDiaryController(foodDiary);
loader.setController(controller);
Parent root = loader.load();
primaryStage.setTitle("Food Diary");
primaryStage.setScene(new Scene(root, 720, 480));
primaryStage.show();
When I run the program I get this error:
Exception in Application start method
java.lang.reflect.InvocationTargetException
...
Caused by: java.lang.NullPointerException at sample.FoodDiaryController.initialize(FoodDiaryController.java:72)
Which is coincidentally the first line of code that references an element in the view:
#FXML private TableView<Food> breakfastTable;
And then in initialise (line 72) which caused the NullPointerException:
breakfastTable.setItems(foodDiary.getBreakfastFoods());
Anyone who could possibly allude to why this is happening?
Prerequisites:
I have to manually set my Controllers since I'm not using a no-arg constructor with my Controllers.
I'm using IntelliJ
I might be wrong and I can't check right now, but I remember some issues when using setController and setControllerFactory. I think when you've specified a fx:controller in your FXML then you can't use setController but must use the setControllerFactory or something like that.
How to get to know which fxml file called the controller class while multiple fxml files have same controller class?
I have an initialize class in which I would like to auto complete two text fields from data in the database. As the controller class is same it throws an error when I run the program. So getting details about which fxml page called the controller class would help.
You shouldn't use the same controller class for different FXML files because then you won't need to deal with problems like this in the first place. However, if you insist you can manually call FXMLLoader.setController before loading the FXML (you also need to remove the reference to the controller inside the FXML), this way you know which controller instance is assigned to which FXML
Assuming you specify the fxml to load by passing a URL, not an InputStream, you simply need to add a URL location field that FXMLLoader can inject a value to. FXMLLoader automatically injects the fxml url to this field:
#FXML
private URL location;
#FXML
private void initialize() {
System.out.println(location);
}
Using the same controller for multiple fxmls with different functionality seems to be bad practice though. Please double check, if using different controllers wouldn't be a cleaner solution.
Note: Every time you load a fxml containing a fx:controller attribute with a controller class name as value, a new instance of the controller is created.
New to javaFx and wanting to use scenebuilder for GUI development, i've come across an issue with no luck searching the website nor the web in general for my problem, although similar questions have been asked, thought a different perspective could be needed. I am trying to load an FXML file through Netbeans after a quick build to test functionality so the code is simple, but i cannot get the root file to be set in the controller. my code is the following
public class Divergex extends Application {
#Override
public void start(Stage stage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("DivergexGUI.fxml"));
Scene scene = new Scene(root);
scene.setRoot(root);
stage.setScene(scene);
stage.show();
}
Ive tried suggestions in changing fxroot to a Vbox with no luck, i continue to get a Load exception on the compile :
Exception in Application start method...
Caused by: javafx.fxml.LoadException: Root hasn't been set. Use method setRoot() before load.
yet when i use
scene.setRoot(root);
the same exception is experienced
i've narrowed the issue down to the fact that my FXML file is unable to be set as a root in the Parent object but have had no luck in tackling this. Any suggestions would be great thanks.
<fx:root> specifies a "dynamic root" for your FXML file; this means the root of the FXML file is an object that is set on the loader prior to loading the file. This is typically used for custom controls, where you want the control to be a subclass of Node that can be instantiated using regular Java code, but want to define its layout using FXML. Proper use of <fx:root> (or at least an example of how it can be used) is shown in the standard documentation. In particular, if you use <fx:root> you must:
Create an FXMLLoader instance, instead of using the static convenience FXMLLoader.load(URL) method
Call setRoot(...) on that instance, and pass in the object that is to be the root of the FXML.
For standard FXML use, you just use a regular instance declaration as the root. Almost every example available works this way: probably the best place to start is the official tutorial. In your case, since you want a VBox, you probably just need
<VBox xmlns="javafx.com/javafx/8"; xmlns:fx="javafx.com/fxml/1"; fx:controller="divergex.DivergexGUIController">
<!-- ... -->
</VBox>
Edit If Netbeans is giving you issues, I recommend using Eclipse with the e(fx)clipse plugin. There's a very barebones, but pretty much all you need, tutorial.
uncheck id::root in scence builder
or change id::root to vbox
Just you should not use fx:root construct in scene builder.
so remove this line of code from the fxml file.
For example: <fx:root prefHeight="246.0" prefWidth="479.0" type="AnchorPane" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.mycontroller">
When you create FXML file with the help of Scene Builder. It uses fx: root as a pane. Replace it with Anchor Pane
AnchorPane xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.controller.Controller
It works for me. Anyone can try, it may help for you
As I understand it, when using FXML to describe a Java FX scene, the controller class is written manually and it's member variables and methods can then be referenced from the .fxml file. When loading the scene using the FXMLLoader, member variables are set to the corresponding scene elements and methods are wired up to the corresponding events automatically. This works but is very cumbersome as changes need to be done in two places and any mistakes will only show up at runtime.
I've seen other GUI frameworks that allow you to instead generate the controller from a scene description as an abstract class which needs to be implemented to access the scene elements and handle the events. An example of what I mean:
I would create the following .fxml file (e.g. using the JavaFX Scene Builder):
<AnchorPane ... >
<children>
<Button fx:id="button" ... text="Button" onAction="#buttonPressed" />
</children>
</AnchorPane>
Somewhere in my build process, the following .java file would be created (e.g. using a Maven plugin):
abstract class TestController {
protected final Parent root;
protected final Button button;
{
// Load test.fxml file
// Assign scene elements to root and button
// Attach event handler to the button that calls buttonClicked()
}
protected abstract void buttonClicked(ActionEvent event);
}
I could then, possibly multiple times, create a concrete implementation of that controller:
final class TestControllerImpl extends TestController {
TestControllerImpl(String buttonLabel) {
button.setText(buttonLabel);
}
#Override
protected void buttonClicked(ActionEvent event) {
button.setText("I've been clicked! What a great day!");
}
}
Is there a project with the goal to do this? Or is there a problem with this approach applied to FXML?
I see the following benefits from this approach:
Declarations for member variables and methods for the controller are automatically generated.
All member variables are final and protected instead of non-final and either public or annotated.
The same for methods, they are protected instead of either public or annotated.
Not implementing a method or misspelling it's name will lead to a compiler error.
Programmatic setup of the scene can be done in the constructor instead of an initialize() method because the constructor will run after the scene has been loaded and its elements assigned to the member variables.
This is now supported in SceneBuilder, NetBeans and in Eclipse. Note this works out of the box in NetBeans and SceneBuilder, but in Eclipse you first need the e(fx)clipse plugin.
SceneBuilder:
With an FXML file open in the editor, enter the menu to select "View" and "Show Sample Controller Skeleton".
Eclipse:
Open the fxml file so the contents are displayed in the code editing pane (you should see the fxml as plaintext xml with syntax highlighting inside Eclipse, not rendered visually in SceneBuilder). Right-click on the code in Eclipse and select "Code" and then "Generate Controller".
NetBeans:
In NetBeans it is even easier, right-click the fxml file in the project explorer and select "Make Controller".
Update Nov 2020
This answer is now outdated.
As various more recent answers have pointed out, there are now a variety of additional different tools available for automatically generating FXML controller classes from FXML documents. Many of these are targeted as extensions, features or plugins to existing development tools, such as SceneBuilder, Idea, Eclipse or NetBeans.
I suggest that interested readers review both this answer and other answers to this question, then look at their individual use-case and toolset chain and choose the solution which is most appropriate for them from the available choices.
There is nothing I know that does exactly what you propose in your question.
Likely this answer will probably end up pretty outdated over time.
Alternate Technologies
JRuby achieves most of your outlined benefits using a slightly different approach - it uses jRuby's dynamic programming magic to automatically create Ruby class members from the FXML dynamically a runtime.
Tom Schindl wrote a tool which generates Java code from FXML. Of the approaches listed in this answer, Tom's tool seems closest to your question.
SceneBuilder Skeletons
A similar Java code generator from FXML is available in SceneBuilder View | Show Sample Controller Skeleton feature, which is described in this blog post. When I use SceneBuilder, I use this feature all the time and try to keep my controllers really light so they are almost all auto generated code from the SceneBuilder skeleton feature.
It is slightly annoying though because it doesn't achieve a clean separation of generated code from hand written code, so you need to be careful when you do updates to the FXML and want to generate a new skeleton and copy and paste it over parts of your existing Controller (plus that is a slightly error prone manual operation that takes a little bit of developer time).
Source code for SceneBuilder is available if you want to see how it works.
Potential Build Tool Plugins
Such a code generation feature might make a worthwhile addition to some of the existing build tools in the JavaFX ecosystem, such as the JavaFX Maven plugin or JavaFX Gradle plugin (or a separate plugin in it's own right).
Future Development
I believe that Oracle are also working on a feature extension for FXML for a future JavaFX release (post Java 8) which compiles FXML directly to Java byte code (class files), bypassing the Java source code step. This kind of feature would probably achieve most of your outlined benefits.
It is possible with NetBeans version 8.
Open FXML , go to Source and click generate controller.
Edit: Now can be done in any IDE , Eclipse needs a plugin thought.
For Intellij Idea IDE users, FXMLManager to the rescue. See the plugin homepage
"When clicking right mouse button on .fxml file, there is new menu item "Update Controller from FXML".
Clicking this item will modify FXML Java Controller:
Remove all #FXML fields that are missing in FXML and their getters/setters
Add all #FXML fields that are missing in Controller
#Deprecate all ActionEvent methods that are missing in FXML
Create all ActionEvent methods that are missing from Controller"
As I know, there are two kind of solutions exist in netbeans.
First, netbeans's internal feature "Make Controller", which you can see with right mouse click on the fxml document. it will generate controller class which will work with FXMLLoader. The controller's java file name should be indicated in the fxml document. (left panel -> Controller -> Controller class)
Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));
Second, netbeans's plugin "FXML 2 JAVA Converter", which you can install from menu (Tool -> Plugin -> Available Plugin -> FXML 2 JAVA Converter). and you can see "Generate Abstract Class" menu item with right mouse click on the fxml document. It will generate source code from fxml document and you can use it as an abstract class without using FXMLLoader like normal JavaFX project not JavaFXML project.
Now you can easily do it with eclipse Just do these simple steps :
Go to your fxml file that you want to create Controller for
Right Click and Click source
Click Generate Controller
Click here to see the Picture of How to do it.
If you're using IntelliJ ide, you may have to try FXML Helper plugin.
First, install the plugin from the File | Settings... | Plugins. After the installation restart the ide, Now right click on the .fxml document and select the FXML Helper menu. That`s all.
#Feuermurmel
no there is not any ways to generate automatically controller class for particula .fxml file.
you should define dynamically declare variable and method with anotation #fxml and set(bind) in scence builder.
I have created a root FXML which is a BorderPane and it has his own root controller.
I want to dynamicly add FXML's to the center of this borderpane.
Each of these fxml's share the same controller, root controller. I have done this in netbeans by choosing an exsisting controller when creating an empty FXML file.
I also have gave the nodes different id names, but the root controller does not recognize the nodes in these fxml's.
Is it possible to share the same controller for different fxml's?
Thanks in advance
Background
I don't know that sharing a controller instance is really recommended, at least I've never seen it done before.
Even if you set the controller class in each of the fxml's you are loading to the same value, it isn't going to share the same controller instance, because every time you load a controller, it will create a new instance (object) of the controller class (which doesn't seem to be what you want).
Potential Solutions
I haven't tried either of these solutions, but believe they will work.
The initialize method will probably be called each time you load a new fxml file. So you will want to account for that in your logic by making initialize idempotent.
A. Manually set the controller instance.
Remove all of the references to your controller class from your fxml files.
Manually create an instance of your controller class.
MyController controller = new MyController();
Set the controller to your controller instance before you load each fxml.
FXMLLoader loader = new FXMLLoader();
loader.setController(controller);
Panel panel = (Panel) loader.load("myfxml.fxml");
Repeat step 3 for each of your fxml files, using the same controller reference each time.
B. Use a controller factory.
You can set a controller factory on your fxml loaders and have the controller factory always return the same controller instance.