CODEWITHSUNDEEP
javafxfocusapplicationwindow
user203921
user203921

Reputation: 31

How to listen for when my application loses focus?

I need to trigger an event when the application window loses focus. How would I set up a listener on the window for that?

Upvotes: 3

Views: 400

Answers (1)

Zephyr
Zephyr

Reputation: 10253

As the comments above suggest, simply listening to your stage's focusedProperty is the right way to do this.

Refer to the simple example application below to see how it works:

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class WindowFocusExample extends Application {

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

    @Override
    public void start(Stage primaryStage) {

        // Simple interface
        VBox root = new VBox(5);
        root.setPadding(new Insets(10));
        root.setAlignment(Pos.CENTER);

        // A label to show our current focus status
        Label label = new Label("Window has focus.");

        // Let's listen for our window to get/lose focus
        primaryStage.focusedProperty().addListener((observable, oldValue, newValue) -> {
            if (newValue) {
                label.setText("Window HAS focus.");
            } else {
                label.setText("Window has LOST focus!");
            }

            System.out.println(label.getText());
        });

        root.getChildren().add(label);

        // Show the Stage
        primaryStage.setWidth(300);
        primaryStage.setHeight(300);
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }
}

Upvotes: 2

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