I'm working on a sudoku solver in javafx and I need to show the algorithm solving. My board is a bunch of buttons laid out in a 9x9 grid and the user enters the puzzle and I solve it.
The solving works fine but I cannot get the algorithm to run. This is what I have but whenever I run the program the window stops responding and I have to terminate the window and get an interrupted by signal 2: SIGINT.
private void loop(Sequence s) {
    long currentTime = System.currentTimeMillis();
    long lastTime = System.currentTimeMillis();
    int x = s.getX();
    int y = s.getY();
    String n = Integer.toString(s.getNum());
    Button button = buttons.get(x).get(y);
    boolean isFinished = true;
    while(isFinished) {
        if(currentTime > lastTime + 400){
            button.setText(n);
            isFinished = false;
        } else {
               currentTime = System.currentTimeMillis();
          }
    }
 public void show(){
   for (Sequence s : sequences){
       loop(s);
    }
}
 
    