But when the queue is empty, remove() throws NoSuchElementException, while poll returns null. They work identically in normal circumstances. So it appears that remove() and poll() are exactly the same.
q.remove(): removes and retrieves the head of the queue.q.peek(): does not remove but only retrieves/returns the head of the queue.q.poll(): removes and retrieves the head of the queue.Let’s “q” be a queue, then here’s how they are different: Week Days: ĭays Updated! ĭays Updated! How poll() is different from peek() and remove()?It is very easy for beginners to mingle up the three different concepts since they look quite similar. We’ll call poll() one by one on weekdays and see what it looks like. Example 2Let’s look at another example of days in a week. Please note, how after each poll() call size of the queue is reduced by 1 and head is returned. Fig 1.1: After using poll() method on a queue poll() method in Java Example 1Have a look at a simple example of calling poll() function on the queue shown in the figure 1.0. And there will be only 4 elements remaining in the queue.
In our example, when you call poll() at the above queue, you’ll receive ‘1’ as a result. Fig 1.0: A simple Queue in Java What is the poll() method of Queue?The poll() method allows you to retrieve and remove the top most element (head) of a Queue. The first element (front) of the queue is also called head. It means the element added to the queue earlier will leave earlier as well. The sooner you enter, the sooner you leave. You can easily imagine it as a queue at a grocery store. What is a Queue?Just like the name implies, Queue is a common data structure in Java following the First In First Out (FIFO) insertion order.
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