The removeFirst() method of LinkedBlockingDeque returns and removes the first element of the Deque container from it. The method throws an NoSuchElementException if the Deque container is empty.
Syntax:
public E removeFirst()
Returns: This method returns the head of the Deque container, which is the first element.
Exception: The function throws a NoSuchElementException if the Deque is empty.
Below programs illustrate removeFirst() method of LinkedBlockingDeque:
Program 1:
// Java Program to demonstrate removeFirst()// method of LinkedBlockingDeque import java.util.concurrent.LinkedBlockingDeque;import java.util.*; public class GFG { public static void main(String[] args) throws InterruptedException { // 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 Dequee System.out.println("Linked Blocking Deque: " + LBD); // removes the front element and prints it System.out.println("First element of Linked Blocking Deque: " + LBD.removeFirst()); // prints the Deque System.out.println("Linked Blocking Deque: " + LBD); }} |
Output:
Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793] First element of Linked Blocking Deque: 7855642 Linked Blocking Deque: [35658786, 5278367, 74381793]
Program 2:
// Java Program to demonstrate removeFirst()// method of LinkedBlockingDeque import java.util.concurrent.LinkedBlockingDeque;import java.util.*; public class GFG { public static void main(String[] args) throws NoSuchElementException { // create object of LinkedBlockingDeque LinkedBlockingDeque<Integer> LBD = new LinkedBlockingDeque<Integer>(); // print Dequee System.out.println("Linked Blocking Deque: " + LBD); try { // throws an exception LBD.removeFirst(); } catch (Exception e) { System.out.println("Exception when removing " + "first element from this Deque: " + e); } }} |
Output:
Linked Blocking Deque: [] Exception when removing first element from this Deque: java.util.NoSuchElementException