Best way to synchronize countdowntimers in JavaFX - javafx

Question

My Programm needs nine Countdowntimers. The timers are started by the user. In my implementation I create a timerclasses for each timer started. The timerclass uses a timeline. Depending on the start of the timers the seconds are asynchrone.
I am not sure how to proceed.
My first thought were to use only 1 timeline for all countdowns. I would put all stringProperties into a list and the timeline will change the property. I am not so sure if this is a good way?
With some google I found out that there is animationtimer which could be used for such a problem. But I couldn't understand the examples. I have to overwrite the handle method. How should I update my timer with this?

Answer 1

The idea is correct: use one animation tool such as PauseTransition or TimeLine (1) to update all counters as demonstrated in the following MRE:
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javafx.animation.PauseTransition;
import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Duration;
public class SyncedCounters extends Application {
private static final int MAX_COUNT = 100;
private Map<Label, Integer> counters;
private VBox countersPane;
#Override public void start(Stage stage) throws IOException {
counters = new HashMap<>();
countersPane = new VBox();
Button addCounter = new Button("Add Counter");
addCounter.setOnAction(e->addCounter());
BorderPane root = new BorderPane(countersPane, null, null, null, addCounter);
stage.setScene(new Scene(new ScrollPane(root),250,200));
stage.show();
update();
}
private void update() {
PauseTransition pause = new PauseTransition(Duration.seconds(1));
pause.setOnFinished(event ->{
updateCounters();
pause.play();
});
pause.play();
}
private void addCounter() {
Label label = new Label(String.valueOf(MAX_COUNT));
label.setAlignment(Pos.CENTER);
label.setPrefSize(150, 25);
counters.put(label, MAX_COUNT);
countersPane.getChildren().add(label);
}
private void updateCounters() {
for(Label l : counters.keySet()){
int counterValue = counters.get(l);
if(counterValue > 0 ){
counterValue--;
l.setText(String.valueOf(counterValue));
counters.put(l, counterValue);
}
}
}
public static void main(String[] args) {
launch(args);
}
}
(1) To use TimeLine instead of PauseTransition change update() to :
void update() {
Timeline timeline = new Timeline();
timeline.setCycleCount(Animation.INDEFINITE);
KeyFrame keyFrame = new KeyFrame(
Duration.seconds(1),
event -> {updateCounters();}
);
timeline.stop();
timeline.getKeyFrames().clear();
timeline.getKeyFrames().add(keyFrame);
timeline.play();
}