@Override
 public String toString() {
   String strOccur = "";
   for (int i = 0; i < WorkerMarks.length; i++) {
     strOccur += String.format("%c=%d ", WorkerMarks[i], occurrences[i]);
   }
   return array.toString() + "\n" + strOccur + "\n";
 }
 public void fillArrayConcurrently() {
   try {
     ArrayWorker[] threads = new ArrayWorker[WorkerMarks.length];
     for (int i = 0; i < WorkerMarks.length; i++) {
       threads[i] = new ArrayWorker(array, MaxWorkerChar, WorkerMarks[i]);
     }
     for (int i = 0; i < WorkerMarks.length; i++) {
       threads[i].start();
     }
     for (int i = 0; i < WorkerMarks.length; i++) {
       threads[i].join();
     }
     for (int i = 0; i < WorkerMarks.length; i++) {
       occurrences[i] = array.countOccurrences(WorkerMarks[i]);
     }
   } catch (InterruptedException e) {
     System.out.println(e.getMessage());
   }
 }