// concurrent/CachedThreadPool3.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
import java.util.*;
import java.util.concurrent.*;
import java.util.stream.*;

public class CachedThreadPool3 {
 public static Integer
 extractResult(Future<Integer> f) {
 try {
 return f.get();
 } catch(Exception e) {
 throw new RuntimeException(e);
 }
 }
 public static void main(String[] args)
 throws InterruptedException {
 ExecutorService exec =
 Executors.newCachedThreadPool();
 List<CountingTask> tasks =
 IntStream.range(0, 10)
 .mapToObj(CountingTask::new)
 .collect(Collectors.toList());
 List<Future<Integer>> futures =
 exec.invokeAll(tasks);
 Integer sum = futures.stream()
 .map(CachedThreadPool3::extractResult)
 .reduce(0, Integer::sum);
 System.out.println("sum = " + sum);
 exec.shutdown();
 }
}
/* Output:
1 pool-1-thread-2 100
0 pool-1-thread-1 100
4 pool-1-thread-5 100
5 pool-1-thread-6 100
8 pool-1-thread-9 100
9 pool-1-thread-10 100
2 pool-1-thread-3 100
3 pool-1-thread-4 100
6 pool-1-thread-7 100
7 pool-1-thread-8 100
sum = 1000
*/