What is the ArrayDeque.removeFirst method in Java?
An Deque interface. ArrayDeque can be used as both Stack or Queue. Null elements are prohibited.
removeFirst method
The removeFirst method gets and removes the first element of the ArrayDeque 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 the same as the
pollFirstmethod except that thepollFirstmethod doesn’t throwNoSuchElementExceptionif theDequeis empty.
Code
The code below demonstrates the use of the removeFirst method:
import java.util.ArrayDeque;class RemoveFirst {public static void main( String args[] ) {ArrayDeque<String> arrayDeque = new ArrayDeque<>();arrayDeque.add("1");arrayDeque.add("2");arrayDeque.add("3");System.out.println("The arrayDeque is " + arrayDeque);System.out.println("arrayDeque.removeFirst() returns : " + arrayDeque.removeFirst());System.out.println("The arrayDeque is " + arrayDeque);}}
Explanation
In the code above:
-
In line 1, we import the
ArrayDequeclass. -
In line 4, we create a
ArrayDequeobject namedarrayDeque. -
From line 5 to 7, we use the
arrayDequeobject to add three elements("1","2","3") toDeque. -
In line 10, we use the
removeFirst()method of thearrayDequeobject to get and remove the first element. In our case,1will be removed and returned.
