DelayQueue is a class provided by Java's concurrency utilities that implements the BlockingQueue interface and is used to hold elements with an associated expiration time. Elements are kept in the queue until their expiration time is reached, at which point they can be removed.

Here are some examples of how to use DelayQueue in Java:

1. Creating a DelayQueue:

DelayQueue<DelayedElement> queue = new DelayQueue<>();

2. Adding elements to the queue:

queue.put(new DelayedElement("element1", 5000));
queue.put(new DelayedElement("element2", 10000));

3. Accessing elements from the queue:

DelayedElement element = queue.take();

4. Iterating over the elements in the queue:

for (DelayedElement element : queue) {
    System.out.println("Element: " + element.getName());
}

5. Removing elements from the queue:

queue.remove(element);

6. Using the peek() method to get the next element in the queue without removing it:

DelayedElement nextElement = queue.peek();

7. Using the poll() method to get the next element in the queue and remove it:

DelayedElement nextElement = queue.poll();

DelayQueue is a useful tool for scheduling events in a multi-threaded application. It allows you to add events to the queue with an associated delay time, and then retrieve and process them when their delay has elapsed. This can be useful for implementing timed events, scheduling tasks, and managing timeouts. The DelayQueue is also useful in situations where you want to implement a blocking queue, but you don't want to block until an element is available.