Check which textbox is selected in javafx - javafx

Question

I have a javafx application with multiple textboxes that the user can enter information in. I also have a keyboard built into the application that when pressed adds that text to the textbox.
My issue is that since I have multiple textboxes, I don't know which one to add the buttons text to. Is there a way in javafx to check if a user has clicked on a certain textbox so I can check which one has been selected and add the text there?

Answer 1

You can use the Scene.focusOwner property of the active scene to get the focused node. Check, if it's a TextInputControl and call the appropriate method for the button clicked. Note that clicking a button may move the focus, if focusTraversable is true for that button. (By default this is the case.)
#Override
public void start(Stage primaryStage) {
GridPane grid = new GridPane();
final Scene scene = new Scene(grid);
for (int i = 0; i < 4; i++) {
grid.add(new TextField(), 0, i);
final String buttonValue = Character.toString((char) ('a'+i));
Button button = new Button(buttonValue);
button.setFocusTraversable(false); // prevent buttons from stealing focus
button.setOnAction(evt -> {
Node fo = scene.getFocusOwner();
if (fo instanceof TextInputControl) {
((TextInputControl) fo).replaceSelection(buttonValue);
}
});
grid.add(button, 1, i);
}
primaryStage.setScene(scene);
primaryStage.show();
}

Answer 2

You should create a listener for each TextField's focusProperty and set an instance variable.
Once you have a global reference to the currently focused TextField, you can do any processing on it that you choose.
Here is a quick application to demonstrate. I've included a couple extra details in the code itself:
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class Main extends Application {
// Instance variable to hold the currently-selected TextField
private TextField selectedTextField;
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
// Create TextFields
TextField txt1 = new TextField();
TextField txt2 = new TextField();
TextField txt3 = new TextField();
TextField txt4 = new TextField();
// This method sets the same change listener on each textfield
installListener(txt1, txt2, txt3, txt4);
VBox pane = new VBox(5);
pane.setPadding(new Insets(5));
// Add the TextFields to the layout
pane.getChildren().addAll(
new HBox(5, new Label("Txt1: "), txt1),
new HBox(5, new Label("Txt2: "), txt2),
new HBox(5, new Label("Txt3: "), txt3),
new HBox(5, new Label("Txt4: "), txt4)
);
primaryStage.setScene(new Scene(pane));
primaryStage.show();
}
// Accepts multiple TextFields
private void installListener(TextField... textFields) {
// Install the same listener on all of them
for (TextField textField : textFields) {
textField.focusedProperty().addListener((observableValue, oldValue, newValue) -> {
// Set the selectedTextField to null whenever focus is lost. This accounts for the
// TextField losing focus to another control that is NOT a TextField
selectedTextField = null;
if (newValue) {
// The new textfield is focused, so set the global reference
selectedTextField = textField;
System.out.println("Selected Text: " + selectedTextField.getText());
}
});
}
}
}