What is the ConcurrentLinkedDeque.removeFirst() method in Java?
The
ConcurrentLinkedDequeis a thread-safe unbounded deque. Thenullvalue is not permitted as an element. We can use theConcurrentLinkedDequewhen multiple threads are sharing a single deque.
The removeFirst method gets and removes the first element of the ConcurrentLinkedDeque object.
Syntax
public E removeFirst()
Parameters
This method doesn’t take any parameters.
Return value
This method retrieves and removes the first element of the deque object. If the deque object is empty, then NoSuchElementException is thrown.
This method is similar to the
pollFirstmethod, except that theremoveFirstmethod throws theNoSuchElementExceptionif the deque is empty, whereas thepollFirstmethod returnsnull.
Code
The code below demonstrates the use of the removeFirst method:
import java.util.concurrent.ConcurrentLinkedDeque;class RemoveFirst {public static void main( String args[] ) {ConcurrentLinkedDeque<String> deque = new ConcurrentLinkedDeque<>();deque.add("1");deque.add("2");deque.add("3");System.out.println("The deque is " + deque);System.out.println("deque.removeFirst() returns : " + deque.removeFirst());System.out.println("The deque is " + deque);}}
Explanation
In the code above:
-
In line 1, we import the
ConcurrentLinkedDequeclass. -
In line 4, we create a
ConcurrentLinkedDequeobject nameddeque. -
From line 5 to 7, we use the
dequeobject to add three elements("1","2","3") todeque. -
In line 10, we use the
removeFirst()method of thedequeobject to get and remove the first element. In our case,1will be removed and returned.
