Executor 3

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;

public class Esempio3
{
    public static void main(String[] args) throws InterruptedException
    {
        ExecutorService executor = Executors.newFixedThreadPool(4);

        ArrayList<Future<Integer>> resultList = new ArrayList<>();

        for (int i = 1; i <= 10; i++) {
            Fattoriale calculator = new Fattoriale(i);
            Future<Integer> result = executor.submit(calculator);
            resultList.add(result);
        }

        executor.awaitTermination(5, TimeUnit.SECONDS);

        //provare anche con executor.shutdown(); e executor.shutdownNow();

        for (int i = 0; i < resultList.size(); i++)
        {
            Future<Integer> result = resultList.get(i);
            Integer number = null;

            try {
                if (result.isDone())
                    number = result.get();
            } catch (InterruptedException e) {}
              catch (ExecutionException e) {System.out.println("Dato non pronto");}
            System.out.printf("Main: Task %d: %d\n", i, number);
        }

        executor.shutdown();
    }
}