Change javafx circles color in certain time using multithreads

Question

I am creating traffic light simulator with javafx that changes colour in every 2 seconds (first red light blinks and remain for 2 seconds) using the concept of multithreading. I

Answer 1

Here is an MCVE that uses Timeline. To get different durations use @fabian Timeline example. This example has a 2-second duration for all lights.

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
import javafx.util.Duration;

/**
 *
 * @author blj0011
 */
public class TrafficLightsFX extends Application
{

    String currentLight = "GREEN";

    @Override
    public void start(Stage primaryStage)
    {
        //Light GUI
        //https://www.color-hex.com/color-palette/35021
        String COLOR_GREEN_DARK = "#008000";
        String COLOR_GREEN = "47C746";
        String COLOR_YELLOW_DARK = "CA7602";
        String COLOR_YELLOW = "FFFF40";
        String COLOR_RED_DARK = "A30504";
        String COLOR_RED = "FF0000";

        Circle red = new Circle(25, Color.valueOf(COLOR_RED_DARK));
        Circle green = new Circle(25, Color.valueOf(COLOR_GREEN_DARK));
        Circle yellow = new Circle(25, Color.valueOf(COLOR_YELLOW_DARK));

        VBox trafficLight = new VBox(red, yellow, green);

        Timeline timeline = new Timeline(new KeyFrame(Duration.seconds(2), (ActionEvent event) -> {
            switch (currentLight) {
                case "GREEN":
                    red.setFill(Color.valueOf(COLOR_RED_DARK));
                    green.setFill(Color.valueOf(COLOR_GREEN));
                    currentLight = "YELLOW";
                    break;
                case "RED":
                    yellow.setFill(Color.valueOf(COLOR_YELLOW_DARK));
                    red.setFill(Color.valueOf(COLOR_RED));
                    currentLight = "GREEN";
                    break;
                case "YELLOW":
                    green.setFill(Color.valueOf(COLOR_GREEN_DARK));
                    yellow.setFill(Color.valueOf(COLOR_YELLOW));
                    currentLight = "RED";
                    break;
            }
        }));
        timeline.setCycleCount(Timeline.INDEFINITE);

        Button btn = new Button();
        btn.setText("Start");
        btn.setOnAction((ActionEvent event) -> {
            switch (timeline.getStatus()) {
                case STOPPED:
                case PAUSED:
                    timeline.play();
                    break;
                case RUNNING:
                    timeline.pause();
                    break;
            }
        });

        VBox root = new VBox(new StackPane(trafficLight), btn);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    {
        launch(args);
    }

}