// Use synchronize to control access. 

class SumArray {
  private int sum; 

  synchronized int sumArray(int nums[]) {
    sum = 0; // reset sum 

    for(int i=0; i<nums.length; i++) { 
      sum += nums[i]; 
      System.out.println("Running total for " +
             Thread.currentThread().getName() +
             " is " + sum); 
      try {
        Thread.sleep(10); // allow task-switch 
      }
      catch(InterruptedException exc) {
        System.out.println("Thread interrupted."); 
      }
    }
    return sum; 
  }
}

class MyThread implements Runnable {
  Thread thrd; 
  static SumArray sa = new SumArray(); 
  int a[]; 
  int answer; 

  // Construct a new thread. 
  MyThread(String name, int nums[]) {
    thrd = new Thread(this, name); 
    a = nums; 
    thrd.start(); // start the thread 
  }

  // Begin execution of new thread. 
  public void run() {
    int sum; 

    System.out.println(thrd.getName() + " starting."); 

    answer = sa.sumArray(a);          
    System.out.println("Sum for " + thrd.getName() +
                       " is " + answer); 

    System.out.println(thrd.getName() + " terminating."); 
  }
}

class Sync {
  public static void main(String args[]) {
    int a[] = {1, 2, 3, 4, 5}; 

    MyThread mt1 = new MyThread("Child #1", a); 
    MyThread mt2 = new MyThread("Child #2", a); 

    try {
      mt1.thrd.join();
      mt2.thrd.join();
    }
    catch(InterruptedException exc) {
      System.out.println("Main thread interrupted.");
    }

  }
}