BlockingDeque removeFirstOccurrence() method in Java with Examples

Last Updated : 14 Oct, 2019

The removeFirstOccurrence() method of BlockingDeque removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it remains unchanged. It returns true if this deque contained the specified element, else it returns false.

Syntax:

public boolean removeFirstOccurrence(Object o)

Parameters: This method accepts a mandatory parameter o which specifies the element to be removed from the Deque container.

Returns: This method returns true if the element is present and removed from the Deque container, else it returns false.

Note: The removeFirstOccurrence() method of BlockingDeque has been inherited from the LinkedBlockingDeque class in Java.

Below programs illustrate removeFirstOccurrence() method of BlockingDeque:

Program 1: When element is present

// Java Program to demonstrate removeFirstOccurrence()
// method of BlockingDeque
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.BlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws InterruptedException
    {
  
        // create object of BlockingDeque
        BlockingDeque<Integer> BD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to end of BlockingDeque
        BD.add(15);
        BD.add(20);
        BD.add(20);
        BD.add(15);
  
        // print Deque
        System.out.println("Blocking Deque: " + BD);
  
        if (BD.removeFirstOccurrence(15))
            System.out.println("Fist occurrence of 15 removed");
        else
            System.out.println("15 not present and not removed");
  
        // prints the Deque after removal
        System.out.println("Blocking Deque: " + BD);
    }
}

Output:

Blocking Deque: [15, 20, 20, 15]
Fist occurrence of 15 removed
Blocking Deque: [20, 20, 15]

Program 2: When element is not present

// Java Program to demonstrate removeFirstOccurrence()
// method of BlockingDeque
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.BlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws InterruptedException
    {
  
        // create object of BlockingDeque
        BlockingDeque<Integer> BD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to end of BlockingDeque
        BD.add(15);
        BD.add(20);
        BD.add(20);
        BD.add(15);
  
        // print Deque
        System.out.println("Blocking Deque: " + BD);
  
        if (BD.removeFirstOccurrence(10))
            System.out.println("Fist occurrence of 10 removed");
        else
            System.out.println("10 not present and not removed");
  
        // prints the Deque after removal
        System.out.println("Blocking Deque: " + BD);
    }
}

Output:

Blocking Deque: [15, 20, 20, 15]
10 not present and not removed
Blocking Deque: [15, 20, 20, 15]

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingDeque.html#removeFirstOccurrence(java.lang.Object)

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