What methods can be used to organize a response waiting mechanism in software systems?

In Java, there are several ways to implement a wait-for-response mechanism:

1. Using wait() and notify()/notifyAll() methods — a classic way of thread synchronization through an object's monitor. A thread calls wait() to suspend execution until notified.

2. Classes from java.util.concurrent:

   • CountDownLatch — allows one or more threads to wait until a certain number of operations have completed.
   • CyclicBarrier — allows a group of threads to wait for each other.
   • Future and CompletableFuture — enable asynchronous result retrieval and waiting for its completion.

3. The join() method — a thread calls join() on another thread to wait for its completion.

4. Synchronization via locks (Lock, Condition) — a more flexible way to manage waiting and notification.

Example with CompletableFuture:

CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
    // Long operation
    return "Result";
});

// Waiting for the result
String result = future.get();
System.out.println(result);