The queue is a data structure that stores elements in a first-in, first-out (FIFO) order. It can be used to implement a priority queue or as a basic synchronization primitive. The remove() method removes an element from the head of this queue and returns it. The poll() method blocks until one or more elements become available for removal, then returns those elements but does not remove them from the queue.
The difference between these two methods is that when you call poll(), it will block until one or more elements become available for removal, then return those elements but does not remove them from the queue; whereas when you call remove(), it removes an element from the head of this queue and returns it immediately without blocking if there are no items in your collection
Differences Between poll() and remove() Methods
The poll() method returns an object of type Element, which represents a queue element. The remove() method throws an exception if the queue is empty, and it returns nothing otherwise.
The remove() method can throw an InterruptedException if it is interrupted while waiting for a lock on this queue’s monitor or performing some other blocking operation (such as dequeuing or popping elements).
poll() Method
The poll() method of Queue is used to remove a value from the queue. It returns the next element in the queue and removes it from the queue at the same time. The syntax of this method is as follows:
Java
public E poll() throws InterruptedException, ExecutionException; |
remove() Method
The remove() method of a Queue<E> removes the oldest element from the queue. The syntax of this method is:
Java
queue.remove(); |
Performance Comparison
The performance comparison between the poll() and remove() methods of Queue in Java is done based on their time complexity and space complexity. The time complexity of the poll() method is O(1), which means it will take constant time to execute this method. In other words, there will be no extra cost for calling this method as compared to calling other methods in Java.
On the other hand, the remove() method has O(n) time complexity where n is the number of elements in the queue at any given point of execution time. This means that every time you call remove(), it takes a linear number of operations (O(1)) to remove one element from the queue which makes it slower than the poll() method when compared side by side because we are writing code inside the loop which executes many times before exiting its body so each iteration takes more than one operation hence increasing overall execution time due to a high number of iterations required per loop iteration.
Conclusion
With this, we can conclude that poll() method is faster than remove() when removing elements from the queue because of its O(1) time complexity. In this article, we will discuss the following topics:
- What is the poll() method in Java?
- When to use the poll() method in Java?
- How to use the poll() method in Java?
In the end, the choice of which method to use depends on your application and its requirements. Polling is good when you don’t want to block threads or in situations where you have a lot of messages coming in at once but need to process them one by one (e.g., a queue for incoming emails). When to Use Poll or Remove?
Polling is generally a better option in the case of a single producer, or multiple consumer scenarios because it gives us control over how long we want to wait for new elements in the queue. It also helps us avoid backpressure which can happen when many threads are attempting to enqueue data into a full queue. If you have a situation where there is only one producer and multiple consumers, then you should use the poll() method. The above explanation will give you a brief idea of how poll() and remove() methods work in Java. We also have a third option called offer(), which is used to insert an element into the queue. It has O(1) time complexity and can be used when we need to add a new element to the queue without removing any existing elements from it.
Difference Between poll() and remove() method of Queue Interface in Java
| Feature | poll() Method | remove() Method |
| Returns | The next element in the queue, or null if the queue is empty. | The next element in the queue, or throws an exception if the queue is empty. |
| Blocks | Blocks until an element becomes available for removal. | Does not block. |
| Time Complexity | O(1) | O(n), where n is the number of elements in the queue. |
| Exceptions | Throws InterruptedException and ExecutionException | Throws NoSuchElementException |
