Set<String> seen = Collections.newSetFromMap(new ConcurrentHashMap<>());
long start = System.currentTimeMillis();
IntStream.range(0, count).parallel().forEach(i -> {
String element = String.valueOf(r.nextInt(items));
if (b.contains(element) && !seen.contains(element))
fp.increment();
b.add(element);
seen.add(element);
});
double fprate = 100.0 * fp.intValue() / count;
System.out.println("False Positives = " + fp + ", FP-Rate = " + fprate);