ConcurrentLinkedDeque removeFirst() method in Java

Last Updated : 18 Sep, 2018

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

// 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

// 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("GeeksforGeeks");
        cld.addFirst("Geeks");

        // 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: [Geeks, GeeksforGeeks, Gfg, GFG]
Element removed : Geeks
Elements inthe LinkedDeque: [GeeksforGeeks, Gfg, GFG]

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentLinkedDeque.html#removeFirst()

Introduction to Java

RICHIK BHATTACHARJEE

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