ConcurrentLinkedDeque removeFirst() method in Java
The ConcurrentLinkedDeque.removeFirst() is an in-built function in Java which removes the first element from the deque container. The function throws a NoSuchElementException if this deque is empty.
Syntax:
Conn_Linked_Deque.removeFirst()
Parameters: The function does not accepts any parameter.
Return Values: The function returns the first element in the deque.
Exception: The function throws a NoSuchElementException if this deque is empty.
Below program illustrates the removeFirst() method:
Program 1: This program involves deque with Integer elements.
// Java Program to demonstrate removeFirst() // method of ConcurrentLinkedDeque import java.util.concurrent.*; class ConcurrentLinkedDequeDemo { public static void main(String[] args) { ConcurrentLinkedDeque<Integer> cld = new ConcurrentLinkedDeque<Integer>(); cld.addFirst( 12 ); cld.addFirst( 70 ); cld.addFirst( 1009 ); cld.addFirst( 475 ); // Displaying the existing LinkedDeque System.out.println( "Elements in" + "the LinkedDeque: " + cld); // Display the first element System.out.println( "Element removed : " + cld.peekFirst()); // Remove the first element cld.removeFirst(); // Displaying the elements System.out.println( "Elements in" + "the LinkedDeque: " + cld); } } |
Output:
Elements inthe LinkedDeque: [475, 1009, 70, 12] Element removed : 475 Elements inthe LinkedDeque: [1009, 70, 12]
Program 2: This program involves deque with String elements.
// Java Program Demonstrate removeFirst() // method of ConcurrentLinkedDeque import java.util.concurrent.*; class ConcurrentLinkedDequeDemo { public static void main(String[] args) { ConcurrentLinkedDeque<String> cld = new ConcurrentLinkedDeque<String>(); cld.addFirst( "GFG" ); cld.addFirst( "Gfg" ); cld.addFirst( "w3wiki" ); cld.addFirst( "Beginner" ); // Displaying the existing LinkedDeque System.out.println( "Elements in" + "the LinkedDeque: " + cld); // Display the first element System.out.println( "Element removed : " + cld.peekFirst()); // Remove the first element cld.removeFirst(); // Displaying the elements System.out.println( "Elements in" + "the LinkedDeque: " + cld); } } |
Output:
Elements inthe LinkedDeque: [Beginner, w3wiki, Gfg, GFG] Element removed : Beginner Elements inthe LinkedDeque: [w3wiki, Gfg, GFG]
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentLinkedDeque.html#removeFirst()