Introduction:

Data structures play a crucial role in software development, enabling efficient manipulation and storage of information. Java provides a wide range of built-in data structures to cater to different needs. In this blog, we will explore how to convert a Deque (Double Ended Queue) into a Queue, emphasizing practical tips and offering multiple approaches.

Method 1: Using LinkedList to Convert Deque to Queue

The LinkedList class in Java implements both the Deque and Queue interfaces, making it a suitable choice for our conversion. This method involves creating a LinkedList object and initializing it with the Deque elements. We then use this LinkedList as a Queue to achieve the desired conversion.

import java.util.Deque;
import java.util.LinkedList;
import java.util.Queue;

public class DequeToQueueConverter {
    public static void main(String[] args) {
        Deque<String> deque = new LinkedList<>();
        deque.add("Element 1");
        deque.add("Element 2");
        deque.add("Element 3");

        Queue<String> queue = new LinkedList<>(deque);

        System.out.println("Converted Queue:");
        while (!queue.isEmpty()) {
            System.out.println(queue.poll());
        }
    }
}

• We start by importing the necessary classes: Deque, LinkedList, and Queue.
• Next, we create a Deque object, deque, and add elements to it using the add() method.
• Then, we create a Queue object, queue, and initialize it with the elements of deque using the LinkedList constructor.
• Finally, we iterate over the queue using the poll() method until it becomes empty, printing each element.

Output:

Converted Queue:
Element 1
Element 2
Element 3

Method 2: Manually Converting Deque to Queue

In this approach, we manually convert the Deque into a Queue by iterating over the elements of the Deque and adding them to a newly created Queue object. This method provides more flexibility if you need to perform any additional operations during the conversion process.

import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Queue;

public class DequeToQueueConverter {
    public static void main(String[] args) {
        Deque<String> deque = new ArrayDeque<>();
        deque.add("Element 1");
        deque.add("Element 2");
        deque.add("Element 3");

        Queue<String> queue = new ArrayDeque<>();
        while (!deque.isEmpty()) {
            queue.add(deque.removeFirst());
        }

        System.out.println("Converted Queue:");
        while (!queue.isEmpty()) {
            System.out.println(queue.poll());
        }
    }
}

• We import the necessary classes: ArrayDeque, Deque, and Queue.
• We create a Deque object, deque, and add elements to it using the add() method.
• Then, we create an empty Queue object, queue.
• We iterate over the deque using a while loop until it becomes empty. In each iteration, we remove the first element from the deque using removeFirst() and add it to the queue using the add() method.
• Finally, we iterate over the queue using a while loop, printing each element after polling it.

Output:

Converted Queue:
Element 1
Element 2
Element 3

Conclusion:

In this blog, we explored practical tips for converting a Deque to a Queue in Java. We discussed two main methods: using the LinkedList class and manually converting the Deque. Both methods yielded the desired output, and we explained their implementation step by step.