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
