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.

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// 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);
    }
}

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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.

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// 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);
    }
}

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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()



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