is there any way to make my loop wait before starting new progress

I tried using thread.sleep()PauseTransitionbut all of them make my program stuckSo, I am hoping to get advice on how I can delay my loop before calling other job

public class LinkedListController implements Initializable {    LinkedList<Job> joblist = new LinkedList<>();    int processnum = DesignController.processnum;    int[] BurstTime = new int[5];    ProgressBar[] progress = new ProgressBar[5];    int CurrentTime = 0;     int StartTime = 0;    @FXML    private Label plabel1,plabel2,plabel3,plabel4,plabel5;     @FXML     ProgressBar progress1,progress2,progress3,progress4,progress5;    double val = 0.0;    Job J;     @FXML    void checkAction(ActionEvent event) throws IOException    {         if(DesignController.Comboboxtext == "FCFS")         {                 J = joblist.removeFirst();             while (joblist.isEmpty()!=true) {                          //  Create a new timeline for each process                    Timeline timeline = new Timeline();                    KeyFrame keyFrame = new KeyFrame(Duration.seconds(J.BurstTime), new KeyValue(J.pbar.progressProperty(), 1));                    timeline.getKeyFrames().add(keyFrame);                   timeline.setOnFinished((EventHandler<ActionEvent>) new EventHandler<ActionEvent>() {                        @Override                        public void handle(ActionEvent event) {                            System.out.println(J.pbar.getId() +" completed");                        }});                   timeline.play();                            }}} }