Java Coding Problems

Combining via anyOf()

Let's assume that we want to organize a raffle for our customers:

List<String> customers = Arrays.asList(  "#1", "#4", "#2", "#7", "#6", "#5");

We can start to solve this problem by defining the following trivial method:

public static CompletableFuture<String> raffle(String customerId) {  return CompletableFuture.supplyAsync(() -> {    Thread.sleep(new Random().nextInt(5000));    return customerId;  });}

Now, we can create an array of CompletableFuture<String> instances, as follows:

CompletableFuture<String>[] cfCustomers = customers.stream()  .map(CustomerAsyncs::raffle)  .toArray(CompletableFuture[]::new);

To find the winner of the raffle, we want to run cfCustomers in parallel, and the first CompletableFuture that completes ...