Java ArrayDeque - pollFirst() Method

The java.util.ArrayDeque.pollFirst() method is used to retrieve and remove the head (first element) of the deque. Every removal of element results into reducing the deque size by one unless the deque is empty. The method returns null, if the deque is empty.

Syntax

public E pollFirst()

Here, E is the type of element maintained by the container.

Parameters

No parameter is required.

Return Value

Returns the head (first element) of the deque, or null if the deque is empty.

Exception

NA.

Example:

In the example below, the java.util.ArrayDeque.pollFirst() method is used to retrieve and remove the head of the given deque.

import java.util.*;

public class MyClass {
  public static void main(String[] args) {
    //creating a ArrayDeque
    ArrayDeque<Integer> MyDeque = new ArrayDeque<Integer>();

    //populating ArrayDeque 
    MyDeque.add(10);
    MyDeque.add(20);
    MyDeque.add(30);

    //printing ArrayDeque
    System.out.println("MyDeque contains: " + MyDeque);

    //deleting first element
    while(MyDeque.size() != 0) {
      System.out.println(MyDeque.pollFirst() + " is deleted from deque.");
   }
  }
}

The output of the above code will be:

MyDeque contains: [10, 20, 30]
10 is deleted from deque.
20 is deleted from deque.
30 is deleted from deque.