// concurrent/IDChecker.java

// (c)2021 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.function.*;

import java.util.stream.*;

import java.util.concurrent.*;

import com.google.common.collect.Sets;

public class IDChecker {

public static final int SIZE = 100_000;

static class MakeObjects

implements Supplier<List<Integer>> {

private Supplier<HasID> gen;

MakeObjects(Supplier<HasID> gen) {

this.gen = gen;

}

@Override public List<Integer> get() {

return

Stream.generate(gen)

.limit(SIZE)

.map(HasID::getID)

.collect(Collectors.toList());

}

}

public static void test(Supplier<HasID> gen) {

CompletableFuture<List<Integer>>

groupA = CompletableFuture

.supplyAsync(new MakeObjects(gen)),

groupB = CompletableFuture

.supplyAsync(new MakeObjects(gen));

groupA.thenAcceptBoth(groupB, (a, b) -> {

System.out.println(

Sets.intersection(

Sets.newHashSet(a),

Sets.newHashSet(b)).size());

}).join();

}

}