BlockingDeque pollFirst() method in Java with examples Last Updated : 01 Oct, 2019 Comments Improve Suggest changes Like Article Like Report The pollFirst() method of BlockingDeque 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. Note: The pollFirst() method of BlockingDeque has been inherited from the LinkedBlockingDeque class in Java. Below programs illustrate pollFirst() method of BlockingDeque: Program 1: Java // Java Program Demonstrate pollFirst() // method of BlockingDeque import java.util.concurrent.LinkedBlockingDeque; import java.util.concurrent.BlockingDeque; import java.util.*; public class GFG { public static void main(String[] args) { // create object of BlockingDeque BlockingDeque<Integer> BD = new LinkedBlockingDeque<Integer>(); // Add numbers to end of BlockingDeque BD.addFirst(7855642); BD.addFirst(35658786); BD.addFirst(5278367); BD.addFirst(74381793); // Print the queue System.out.println("Blocking Deque: " + BD); // prints and deletes System.out.println("Front element in Deque: " + BD.pollFirst()); // Deque after deletion of front element System.out.println("Blocking Deque: " + BD); } } Output: Blocking Deque: [74381793, 5278367, 35658786, 7855642] Front element in Deque: 74381793 Blocking Deque: [5278367, 35658786, 7855642] Program 2: Java // Java Program Demonstrate pollFirst() // method of BlockingDeque // when Deque is empty import java.util.concurrent.LinkedBlockingDeque; import java.util.concurrent.BlockingDeque; import java.util.*; public class GFG { public static void main(String[] args) { // create object of LinkedBlockingDeque LinkedBlockingDeque<Integer> BD = new LinkedBlockingDeque<Integer>(); // Add numbers to end of BlockingDeque BD.add(7855642); BD.add(35658786); BD.add(5278367); BD.add(74381793); // Print the queue System.out.println("Blocking Deque: " + BD); // empty deque BD.clear(); System.out.println("Front element in Deque: " + BD.pollFirst()); } } Output: Blocking Deque: [7855642, 35658786, 5278367, 74381793] Front element in Deque: null Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingDeque.html#pollFirst(long, %20java.util.concurrent.TimeUnit) Comment More infoAdvertise with us Next Article BlockingDeque pollFirst() method in Java with examples G gopaldave Follow Improve Article Tags : Java Java-Collections Java-Functions java-interfaces Practice Tags : JavaJava-Collections Similar Reads BlockingDeque poll() method in Java with examples The poll() method of BlockingDeque 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 the cont 2 min read BlockingDeque pollLast() method in Java with examples The pollLast() method of BlockingDeque returns the last element in the Deque container, and deletes it. It returns null if the container is empty. Syntax: public E pollLast() Parameters: This method does not accept any parameters. Returns: This method returns last element in the Deque container if t 2 min read BlockingDeque putFirst() method in Java with Examples The putFirst(E e) method of BlockingDeque inserts the specified element at the front of the queue represented by this deque. If the Deque is capacity restricted, then it will wait for the space to become available. Syntax: public void putFirst(E e) Parameters: This method accepts a mandatory paramet 2 min read BlockingDeque offerFirst() method in Java with Examples The offerFirst(E e) method of BlockingDeque 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) Parameters: 2 min read BlockingDeque takeFirst() method in Java with Examples The takeFirst() method of BlockingDeque returns and removes the first element of the Deque container from it, waiting if necessary until an element becomes available.. The method throws an InterruptedException if it is interrupted while waiting. Syntax: public E takeFirst() Returns: This method retu 2 min read Like