使用ExecutorService,怎么获取invokeAll所有线程的id

public static int getFinalResultPar(String s) throws FileNotFoundException,InterruptedException,ExecutionException{                ExecutorService executor = Executors.newFixedThreadPool(8);        Scanner scanner2 = new Scanner(new File(s));        int fR = 0;                List<Callable<Integer>> tasks = new ArrayList<Callable<Integer>>();                    while(scanner2.hasNextLine()){            final Scanner lineScanner2 = new Scanner(scanner2.nextLine());                        Callable<Integer> c = new Callable<Integer>() {                public Integer call() {                                        return getDivisorsSum(calSummedUpSum(calOneLine(lineScanner2)));                }            };            tasks.add(c);        }        List<Future<Integer>> futures = executor.invokeAll(tasks);                for (Future<Integer> fs: futures) {            int res = fs.get();            fR += res;        }        executor.shutdown();        return fR;    }