Future task is done or not ?

[Edward Chen]

In the Future, does the main thread need to wait for the future job ?

for example

ExecutorService pool = Executors.newFixedThreadPool(2);
Future<BigInteger> p = pool.submit(new PrimeSearch(512));
Future<BigInteger> q = pool.submit(new PrimeSearch(512));
 
// Line A
BigInteger product = p.get().multiply(q.get());

in the Line A, why we not need to make sure if the thread job is done ? something like

while(p.isNotDone() || q.isNotDone()){
   thread.currentThread().wait();
}

Then next question is , how could we implement this: if p, q thread is not done in 10s, main thread will throw exception and terminate the logic.

Thanks

[Jim Yingst]

The get() method in Future is defined to block until the task has completed, or until an exception is thrown. So this is already taken care of for you. There's no need to implement waiting.
[ January 20, 2008: Message edited by: Jim Yingst ]

[vu lee]

As Jim stated, get() method will block the current thread till the task is done. You could call the overloaded method get(10,TimeUnit.SECONDS) which would block about 10 seconds then throw Timeout Exception if it the task has not been completed.