ConcurrentLinkedDeque removeLastOccurrence() Method in Java

The java.util.concurrent.ConcurrentLinkedDeque.removeLastOccurrence() method is an in-built method in Java which accepts a parameter and removes the last appearance of that element in the deque. Thus, in case the element is not present in the deque, it remains unchanged.

Syntax:

public boolean removeLastOccurrence(Object o)

Parameters: The function accepts an object elem as parameter which denotes the object whose last appearance from the deque is to be removed.

Return Value: The function returns true if elem is present in th edeque and returns false otherwise.

Exception: The function throws NullPointerException if the specified element passed as parameter to the function is null.

Below programs illustrate the use of removeLastOccurrence() method :

/* Java program to demonstrate  
   removeLastOccurrence() 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("Geeks"); 
        cld.addFirst("Gfg"); 
        cld.addFirst("gfg"); 
        cld.addFirst("Geeks"); 
  
        // Displaying the existing LinkedDeque 
        System.out.println("Elements in "
                           + "the LinkedDeque: " + cld); 
  
        // Remove last occurrence of  element 
        cld.removeLastOccurrence("Geeks"); 
  
        // Displaying the modified LinkedDeque 
        System.out.println("Elements in "
                           + "the LinkedDeque: " + cld); 
    } 
} 

Output:

Elements in the LinkedDeque: [Geeks, gfg, Gfg, Geeks, GFG]
Elements in the LinkedDeque: [Geeks, gfg, Gfg, GFG]

Program 2:

/* Java program to demonstrate  
   removeLastOccurrence() 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(280); 
        cld.addFirst(1008); 
        cld.addFirst(1050); 
        cld.addFirst(379); 
  
        // Displaying the existing LinkedDeque 
        System.out.println("Elements in "
                           + "the LinkedDeque: " + cld); 
        try { 
            // Remove last occurrence of  element 
            cld.removeLastOccurrence(null); 
        } 
        catch (Exception e) { 
            System.out.println(e); 
        } 
    } 
} 

Output:

Elements in the LinkedDeque: [379, 1050, 1008, 280, 12]
java.lang.NullPointerException

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

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