What is the ConcurrentLinkedQueue.remove(Object o) in Java?

The remove method is used to remove the first occurrence of the specified element in the ConcurrentLinkedQueue object. If the element is not present, then no action is performed.

The ConcurrentLinkedQueue is a thread-safe unbounded queue. The elements are ordered by FIFOFirst-In-First-Out. The elements are inserted at the tail (end) and retrieved from the head (start) of the queue. The null elements are not allowed as an element of the queue. We can use the ConcurrentLinkedQueue when multiple threads are sharing a single queue.

Syntax

public boolean remove(Object o)

Parameter

This method takes the element to be removed from the queue as a parameter.

Return value

This method returns true if the queue contains the specified element. Otherwise, false is returned.

Code

The below code demonstrates how to use the remove(Object o) method:

import java.util.concurrent.ConcurrentLinkedQueue;
class Remove {
    public static void main( String args[] ) {
      ConcurrentLinkedQueue<String> queue = new ConcurrentLinkedQueue<>();
      queue.add("1");
      queue.add("2");
      queue.add("1");
      System.out.println("The queue is " + queue);
      
      System.out.println("Is element 1 present & removed: " + queue.remove("1"));
      System.out.println("The queue is " + queue);
      System.out.println("\nIs element 4 present & removed: " + queue.remove("4"));
      System.out.println("The queue is " + queue);
    }
}

Explanation

In the above code:

In line 1, we imported the ConcurrentLinkedQueue class.
In line 4, we created a ConcurrentLinkedQueue object with the name queue.
From line 5 to 7, we used the add() method of the Queue object to add three elements ("1","2","3") to queue.
On line 10, we used the remove(Object o) method to remove the first occurrence of the element "1". The element "1" is present in two indexes, 0 and 2. After calling this method, the element at index 0 will be removed and true will be returned.
On line 13, we used the remove(Object o) method to remove the first occurrence of the element "4". The element "4" is not present. So, queue remains unchanged and this method returns false.

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