Queue Remove Method in Java

Approach 2: LinkedList

The space required for the linked representation of a queue is O(n),where n is the number of elements in the queue, while the time required for operations is O(1).

Code

import java.util.*;

public class Solution {
  public static void main(String[] args)
  throws IllegalStateException{

      // create object of Queue
     Queue<Integer> q = new LinkedList<Integer>();

     // Add numbers to end of Queue
     q.add(7);
     q.add(3);
     q.add(5);
     q.add(4);

     // print queue
     System.out.println("Queue: " + q);

     // print head and deletes the head
     System.out.println("Queue's head: " + q.remove());

     // print queue after using remove() method
     System.out.println("Queue: " + q);
 
    // print head and deleted the head
    System.out.println("Queue's head: " + q.remove());
  }
}

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Output

Approach 3: Exception throw method

Code

import java.util.*;

public class Solution {
    public static void main(String[] args)
    throws IllegalStateException{

       // create object of Queue
       Queue<Integer> q = new LinkedList<Integer>();

      // Add numbers to end of Queue
      q.add(7);
      q.add(3);

      // print queue
      System.out.println("Queue: " + q);

      // print head and deletes the head
      System.out.println("Queue's head: " + q.remove());

     // print queue after using the method
     System.out.println("Queue: " + q);

     // print head and deleted the head
    System.out.println("Queue's head: " + q.remove());

    // print queue
    System.out.println("Queue: " + q);

    try {
       // Queue is empty 
       System.out.println("Queue's head: " + q.element());
    }
    catch (Exception e) {
       System.out.println("Exception: " + e);
    }
  }
}

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Output

Frequently Asked Questions

Difference between stack and queue?

             Stack

• Based on the LIFO principle.
• Insert operation is done by push() method.
• The delete operation is done by the pop() method.
• Insertion and deletion in stacks take place only from one end.

             Queue

• Based on the FIFO principle.
• Insert operation is done by enqueue () method.
• Deletion operation is done by dequeue() method.
• Insertion and deletion in queues take place from the opposite ends of the list.                                      

Different methods to implement remove() method in a queue?

It can be implemented using LinkedList, arraydeque, ConcurrentLinkedDeque.

Difference between remove() and poll() method in queue?

The remove() method throws an exception if the list is empty, which is not in the poll() method.

Conclusion

In this blog, we covered the remove() method of the queue, with their implementation using various approaches in the Java language. You can check out more related to queue data structure for using it in your codes to increase efficiency.

Recommended Readings:

• Advantages of Circular Queue
• Queue Data Structure in Java
• Difference between Array and Deque in C++
• Love Babbar DSA Sheet

Do check out The Interview guide for Product Based Companies as well as some of the Popular Interview Problems from Top companies like Amazon, Adobe, Google, Uber, Microsoft, etc. on Coding Ninjas Studio.

To learn more about Data Structures and Algorithms, you can enroll in our course on DSA in Java.

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