Java's Linked list class offers a function that allows a "
Queue Based" working called poll(). This function not only returns deletes the first element, but
also displays them while being deleted and hence can have a lot of usage in daily life problems and competitive programming as well. There are
3 variants of poll(), all three are discussed in this article.
1. poll() : This method
retrieves and
removes the
head (first element) of this list.
Declaration :
public E poll()
Return Value :
This method returns the first element of this list, or null if this list is empty.
Output :
The initial Linked List is : [Geeks, 4, Geeks, 8]
Head element of the list is : Geeks
Linked List after removal using poll() : [4, Geeks, 8]
2. pollFirst() : This method
retrieves and
removes the
first element of this list, or returns null if this list is empty.
Declaration :
public E pollFirst()
Return Value :
This method returns the first element of this list, or null if this list is empty
Output :
The initial Linked List is : [Geeks, 4, Geeks, 8]
Head element of the list is : Geeks
Linked List after removal using pollFirst() : [4, Geeks, 8]
3. pollLast() : This method
retrieves and
removes the
last element of this list, or returns null if this list is empty.
Declaration :
public E pollLast()
Return Value :
This method returns the last element of this list, or null if this list is empty.
Output :
The initial Linked List is : [Geeks, 4, Geeks, 8]
Tail element of the list is : 8
Linked List after removal using pollLast() : [Geeks, 4, Geeks]
Practical Application : This function has potential usage in the "
queue management" systems and also in "1st elimination" games that can be thought of. The former example is discussed below.
