// threads/ParallelStreamPuzzle2.java

// (c)2016 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://mindviewinc.com/Books/OnJava/ for more book information.

import java.util.*;

import java.util.function.*;

import java.util.stream.*;

import java.util.concurrent.*;

import java.nio.file.*;

public class ParallelStreamPuzzle2 {

public static ConcurrentLinkedDeque<String> trace =

new ConcurrentLinkedDeque<>();

static class

IntGenerator implements Supplier<Integer> {

private int current = 0;

public synchronized Integer get() { // (1)

trace.add(current + ": " +

Thread.currentThread().getName());

return current++;

}

}

public static void main(String[] args) throws Exception {

List<Integer> x = Stream.generate(new IntGenerator())

.limit(10)

.parallel()

.collect(Collectors.toList());

System.out.println(x);

Files.write(Paths.get("PSP2.txt"), trace);

}

}

/* Output:

[2, 3, 4, 5, 6, 7, 8, 9, 10, 63]

*/