Why can't I do .set...Anchor on the anchor pain? (JavaFx)

[bwefoi oiwej]

I created a window with the Scenebuilder.

In the controller class I called my anchor-panel which I created in the Scenebuilder., I saved the anchor pane in a variable, the name of the variable is called anchorpane1,

First I wanted to add a shape to it, which I created in the controller class, for that I wanted to do:
anchorpane1.getchildren().add() and in add then my shape purely, that is correct right?

But my next problem, I wanted to set anchors to the shape, that is possible with .setTopAnchor, .setRigthAnchor, .set.LeftAnchor and .setBottomAnchor.

But when I take my anchor panel, I can't do .set...Anchor, why? That does not work

[Piet Souris]

hi bwefoi,

welcome to the Ranch and enjoy the stay!

Without seeing any code, it is hard to tell what is going wrong. What I can say for now is that the method 'setXXXAnchor' is a static method, and therefore you should use something like:

AnchorPane.setTopAnchor( someComponent, 10.0d );
AnchorPane.setRightAnchor( someComponent, 10.0d );

[bwefoi oiwej]

Piet Souris wrote:hi bwefoi,

welcome to the Ranch and enjoy the stay!

Without seeing any code, it is hard to tell what is going wrong. What I can say for now is that the method 'setXXXAnchor' is a static method, and therefore you should use something like:

AnchorPane.setTopAnchor( someComponent, 10.0d );
AnchorPane.setRightAnchor( someComponent, 10.0d );

Thank you my code is:

public class Controller { 

  @FXML 
   private AnchorPane test;


   public void initalize(){


    /forExample
    test.setRightAnchor(...) //(don´t work, I can´t make test.setRightAnchor)
   }



}

[Piet Souris]

Well, it DOES work when you type

test.setRightAnchor(...)

however, in the IDE that I use (NetBeans 12.5), when I type

test.

then this method does NOT show up. It does when I type

AnchorPane.

Here is an example:

public class AnchorPaneApp extends Application {
    
    @Override
    public void start(Stage primaryStage) throws Exception {

        var ap = new AnchorPane();

        // two circles
        var c1 = new Circle(30.0);
        c1.setFill(Color.BLUEVIOLET);
        var c2 = new Circle(60);
        c2.setFill(Color.GREENYELLOW);

        ap.getChildren().addAll(c1, c2);
        
        ap.setTopAnchor(c1, 10.);
        // here I get the warning that I am accessing a static method
        ap.setLeftAnchor(c1, 10.);
        ap.setBottomAnchor(c2, 10.);
        ap.setRightAnchor( c2, 10.);

        Scene scene = new Scene(ap, 300, 150);

        primaryStage.setTitle("AnchorPaneApp");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

People in the know at this site always stress that you should call static methods with 'Class.method' and not with 'instance.static method'.

[Campbell Ritchie]

Moved to our FX forum.

And welcome to the Ranch (again).

[Lou Hamers]

Piet is correct about using the AnchorPane.setTopAnchor() static method reference.

You CAN access the static method on AnchorPane via a AnchorPane instance reference, but it's considered a bad practice.
I would say for the following reasons (at least):
-It harms readability (it looks like calling a regular instance method so it's misleading).
-It's more fragile - you're required to have an instance reference. If the AnchorPane reference you're calling the method on is null, you'll get an NPE. A static method reference won't NPE like that (unless you pass a null parameter maybe).

Hopefully your IDE warns you - don't ignore warnings. IntelliJ's warning about this:


So use this form:
AnchorPane.setTopAnchor(someChildComponentInstance, 10.0);

So:

    @FXML
    private AnchorPane initialAp;
    @FXML
    private VBox testingVb;
    
    @Override
    public void initialize(URL location, ResourceBundle resources) {
        AnchorPane.setRightAnchor(testingVb, 10.0);
    }

There's a few other times you use these static methods in JFX too, notably VBox.setVgrow() and HBox.setHgrow(), and I think a few others. They're really important for doing anything other than trivial layouts in JFX. Although if you use SceneBuilder (strongly suggested), you rarely need to worry about these.