LinkedList?Linked List is a collection of linear data elements. Each element (node) contains data and reference parts. The data part has the value and the reference part has the address link to the next element.
The elements are not indexed so random access like Array is not possible. Instead, we traverse from the beginning of the list and access the elements.
In Java, the
LinkedListis theimplementation of the List and Deque interfaces. The Doubly-linked list Each node contains three fields: two link fields(one for the previous element and another for the next element) and one data field. LinkedListclass present in thejava.utilpackage.
poll method of the LinkedList class?The poll method can be used to get and remove the first element (head element) of the LinkedList.
public E poll();
This method doesn’t take any arguments.
This method retrieves and removes the first element of the list. If the list is empty then null is returned.
The code below demonstrates how to use the poll method.
import java.util.LinkedList;class LinkedListPoll {public static void main( String args[] ) {LinkedList<String> list = new LinkedList<>();list.add("1");list.add("2");list.add("3");System.out.println("The list is " + list);System.out.println("list.poll() returns : " + list.poll());System.out.println("The list is " + list);}}
In the code above:
In line 1, we imported the LinkedList class.
In line 4, we created a LinkedList object with the name list.
From lines 5 to 7, we used the add method of the list object to add three elements ("1","2","3") to the list.
In line 10, we used the poll method of the list object to get and remove the first element.