LinkedBlockingDeque pollFirst() method in Java Last Updated : 14 Sep, 2018 Comments Improve Suggest changes Like Article Like Report The pollFirst() method of LinkedBlockingDeque returns the front element in the Deque container, and deletes it. It returns null if the container is empty. Syntax: public E pollFirst() Parameters: This method does not accept any parameters. Returns: This method returns front element in the Deque container if the container is not empty and deletes the element. It returns null if the container is empty. Below programs illustrate pollFirst() method of LinkedBlockingDeque: Program 1: Java // Java Program Demonstrate pollFirst() // method of LinkedBlockingDeque import java.util.concurrent.LinkedBlockingDeque; import java.util.*; public class GFG { public static void main(String[] args) { // create object of LinkedBlockingDeque LinkedBlockingDeque<Integer> LBD = new LinkedBlockingDeque<Integer>(); // Add numbers to end of LinkedBlockingDeque LBD.addFirst(7855642); LBD.addFirst(35658786); LBD.addFirst(5278367); LBD.addFirst(74381793); // Print the queue System.out.println("Linked Blocking Deque: " + LBD); // prints and deletes System.out.println("Front element in Deque: " + LBD.pollFirst()); // Deque after deletion of front element System.out.println("Linked Blocking Deque: " + LBD); } } Output: Linked Blocking Deque: [74381793, 5278367, 35658786, 7855642] Front element in Deque: 74381793 Linked Blocking Deque: [5278367, 35658786, 7855642] Program 2: Java // Java Program Demonstrate pollFirst() // method of LinkedBlockingDeque // when Deque is empty import java.util.concurrent.LinkedBlockingDeque; import java.util.*; public class GFG { public static void main(String[] args) { // create object of LinkedBlockingDeque LinkedBlockingDeque<Integer> LBD = new LinkedBlockingDeque<Integer>(); // Add numbers to end of LinkedBlockingDeque LBD.add(7855642); LBD.add(35658786); LBD.add(5278367); LBD.add(74381793); // Print the queue System.out.println("Linked Blocking Deque: " + LBD); // empty deque LBD.clear(); System.out.println("Front element in Deque: " + LBD.pollFirst()); } } Output: Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793] Front element in Deque: null Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingDeque.html#pollFirst() Comment More infoAdvertise with us Next Article LinkedBlockingDeque pollFirst() method in Java G gopaldave Follow Improve Article Tags : Misc Java Java-Collections Java - util package Java-Functions Java-LinkedBlockingDeque +2 More Practice Tags : JavaJava-CollectionsMisc Similar Reads LinkedBlockingDeque pop() method in Java The pop() method of LinkedBlockingDeque pops an element from the stack represented by this deque. In other words, it removes and returns the first element of this deque. It returns null if the container is empty. Syntax: public E pop() Parameters: This method does not accept any parameters. Returns: 2 min read LinkedBlockingDeque getFirst() method in Java The getFirst() method of LinkedBlockingDeque returns the front most element in the Deque container. If the LinkedBlockingDeque is empty, then on function call it returns a NoSuchElementException. Syntax: public E getLast() Parameters: This method does not accept any parameters. Returns: This method 2 min read LinkedBlockingDeque clear() method in Java The clear() method of LinkedBlockingDeque erases all the elements that are present in the LinkedBlockingDeque container. The container becomes empty after the function is called. Syntax: public void clear() Parameters: This method does not accepts any parameters Returns: This method does not returns 2 min read LinkedBlockingDeque getLast() method in Java The getLast() method of LinkedBlockingDeque returns the last element in the Deque container. If the LinkedBlockingDeque is empty, then on function call it returns a NoSuchElementException. Syntax: public E getLast() Parameters: This method does not accept any parameters. Returns: This method returns 2 min read LinkedBlockingDeque descendingIterator() method in Java The descendingIterator() method of LinkedBlockingDeque returns an iterator over the elements in this deque in a reverse sequential order. The elements will be returned in order from last(tail) to first(head). The returned iterator is a "weakly consistent" iterator. Syntax: public Iterator descending 2 min read LinkedBlockingDeque peekFirst() method in Java The peekFirst() method of LinkedBlockingDeque returns the front element in the Deque container, but does not deletes it. It returns null if the container is empty. Syntax: public E peekFirst() Parameters: This method does not accept any parameters. Returns: This method returns front element in the D 2 min read LinkedBlockingDeque offerFirst() method in Java The offerFirst(E e) method of LinkedBlockingDeque inserts the element passed in the parameter at the front of the Deque container. If the container's capacity has exceeded, then it does not returns an exception as in case of add() and addFirst() function. Syntax: public boolean offerFirst(E e) Param 2 min read LinkedBlockingDeque push() method in Java The push(E e) method of LinkedBlockingDeque pushes an element onto the stack represented by this deque. It inserts the element passed in the parameter to the front of the Deque if there is space. If the LinkedBlockingDeque is capacity restricted and no space is left for insertion, it returns an Ille 2 min read LinkedBlockingDeque peek() method in Java The peek() method of LinkedBlockingDeque returns the front element in the Deque container. It returns null if the container is empty. Syntax: public E peek() Parameters: This method does not accept any parameters. Returns: This method returns front element in the Deque container if the container is 2 min read LinkedBlockingDeque poll() method in Java The poll() method of LinkedBlockingDeque returns the front element in the Deque container and deletes it. It returns null if the container is empty. Syntax: public E poll() Parameters: This method does not accept any parameters. Returns: This method returns front element of the Deque container if th 2 min read Like