Syncronized method in Java

gistfile1.java

    public static synchronized void addValue(int myIndex) {
        boolean imDone = false;
        System.out.println("Thread " + myIndex + " is trying to add its value");
            do {
                if (myIndex != numberOfThreadsDone) {
                    try {
                        System.out.println(myIndex + " is about to wait");
                        ParallelSerial.class.wait(); // <-- ** Important need to call className.class.wait() in syncronized method**
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                } else {
                    sum += arrayToSum[myIndex];
                    numberOfThreadsDone++;
                    imDone = true;
                    ParallelSerial.class.notifyAll(); // <-- ** Important need to call className.class.notifyAll() in syncronized method **
                }
            } while (!imDone);
    }