Throttling javafx gui updates

This is the idiom used in the Task class for implementing the updateMessage(...) method, and other similar methods. It provides a nice, robust solution to avoid flooding the FX Application Thread:

import java.util.concurrent.atomic.AtomicLong;

import javafx.application.Application;
import javafx.application.Platform;
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 ThrottlingCounter extends Application {

    @Override
    public void start(Stage primaryStage) {
        final AtomicLong counter = new AtomicLong(-1);
        final Label label = new Label();
        final Thread countThread = new Thread(new Runnable() {
            @Override
            public void run() {
                long count = 0 ;
                while (true) {
                    count++ ;
                    if (counter.getAndSet(count) == -1) {
                        updateUI(counter, label);
                    }
                }
            }
        });
        countThread.setDaemon(true);
        countThread.start();

        VBox root = new VBox();
        root.getChildren().add(label);
        root.setPadding(new Insets(5));
        root.setAlignment(Pos.CENTER);

        Scene scene = new Scene(root, 150, 100);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void updateUI(final AtomicLong counter,
            final Label label) {
        Platform.runLater(new Runnable() {
            @Override
            public void run() {
                final String msg = String.format("Count: %,d", counter.getAndSet(-1));
                label.setText(msg);
            }
        });
    }

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

The AtomicLong holds the current value to be used to update the Label. The count continually increments and updates the AtomicLong, but only schedules a call to Platform.runLater(...) if it’s current value is -1. The Platform.runLater(...) updates the Label with the current value from the AtomicLong and flips the AtomicLong back to -1, indicating that it’s ready for a new update.

The effect here is to schedule new calls to Platform.runLater(...) whenever the FX Application Thread is ready to handle them. There’s no hard-coded time interval which could need tuning.

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