Gainer Focus and Lost Focus

Question

How implements the methods to gainer focus and lost focus?
Thanks

Answer 1

Use a node.focusedProperty() change listener to know when a field gains or loses focus.
Call node.requestFocus() to ask for focus (for some reason I have to wrap this in Platform.runLater to get it to actually do anything).
Call node.setFocusTraversable(false) if you don't want the user to be able to tab to the node, but still be able to click on the node to give it focus.
Call node.setDisable(true) if you don't want the node to be focusable at all.
I'm not sure how the focus traversable order is calculated, perhaps the order that items are added to the scene?
Not sure how you would create a custom focus traverse if you needed one.
  @Override public void start(Stage primaryStage) {
    final TextField tf1 = new TextField("First but not initially focused");
    final TextField tf2 = new TextField("Second initially focused");
    Platform.runLater(new Runnable() { public void run() { tf2.requestFocus(); } });
    final TextField tf3 = new TextField("Can focus by clicking on, but not by tabbing to.");
    tf3.setFocusTraversable(false);
    final TextField tf4 = new TextField("Cannot focus at all.");
    tf4.setDisable(true);
    tf1.focusedProperty().addListener(new ChangeListener<Boolean>() {
        public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
          if (newValue) {
            System.out.println("First text field gained focus");
          } else {
            System.out.println("First text field lost focus");
    VBox root = new VBox(); root.setSpacing(5);
    root.getChildren().addAll(tf1, tf2, tf3, tf4);
    primaryStage.setScene(new Scene(root, 300, 100));
    primaryStage.show();
  }