Hello @chook ,

Do you have the String[] args for run test ??? :)
Thanks

http://blog.takipi.com/framework-forkjoin-vs-flujos-paralelos-vs-executorservice-el-benchmark-definitivo-al-forkjoin/

In the final comparison return collect.size() == 0; it should be return collect.size() == TestPrime.numberOfThread.intValue(); since the filter predicate lets all parts pass that succeeded the isPrime() test. So if all threads pass it, it's a prime.
Test it with a simple number, e.g. "19" and it would return false.