Dealing with a turn based application with using a global static variable

Question

Hi there. I read some articles about JavaFX concurrency,so as a newbie i have to practice on it. Now i'm trying to implement a turn based application that can be played among 3-6 players. Moreover, i use a scene imported from a .fxml file and i have to update it correctly depends on some calculations of each thread (in other word players ). My main issue is, i don't wanna use a while loop which checks the state of game like;
while( GameState != State.GAME_OVER ){
     currentPlayer = GameBoard.getNextPlayer();
     // do some actions,calculations etc.
So, i want to use worker threads instead of this while loop. I guess using Service class for iterating and assigning the next player will be suitable instead of using the while loop and Tasks for doing each player's calculation,or waiting for some responses from Human players on UI based,however, i'm struggling with two problems.
There should a global static variable ( like GameState which is an Enumarator ) determines the state of the game,so it should be updated and should be checked by each turn. Is there any way to do this ?
How can i get rid off this while loop ?
I will appreciate for every answer. Thanks anyway.

Answer 1

It shouldn't make too much difference. The basic idea is that you have a model class representing your game state (the Game class in jsmith's example). When a player makes a move, you update the state of the game. Since this will result in changes to the UI, this update should be performed on the FX Application Thread.
If the player making the move is a human player, the move will likely be made by a user action (button press or mouse click, etc); this will be handled on the FX Application thread anyway.
When the state of the game changes so it is the turn of an "artificial" player to make a move, have the object representing the artificial player calculate its next move, and then update the game state. Since this is a response to the game state changing (it's now the turn of the artificial player), this will also be on the FX Application Thread.
The only (slight) complexity comes if the calculation of the move for the artificial player takes a long time. You don't want to perform this long running calculation on the FX Application Thread. The cleanest way to manage this is to launch a Task which calculates the desired move, and then updates the game state when the move is ready. So, something like this:
GameState game = ... ;
// UI is bound to the game state.
ExecutorService executorService = ... ;
final Player currentPlayer = game.getCurrentPlayer() ;
final Task<Move> calculateMoveTask = new Task<Move>() {
     @Override
     public Move call() {
          Move move = // compute next move...
          return move ;
calculateMoveTask.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
     @Override
     public void handle(WorkerStateEvent event) {
          gameState.makeMove(currentPlayer, calculateMoveTask.getValue());
executorService.submit(calculateMoveTask);
If you're doing more threading than that, you're probably doing it wrong... . There should also be no need for anything to be held as a "global" static variable (the idea above is the only structural modification you need to the example posted by jsmith).