Java Program to Reverse a Queue

import java.util.*;
class Queue
{
  int front, rear, size;
  int capacity;
  int[] array;

  public Queue (int capacity)
  {
    this.capacity = capacity;
    front = this.size = 0;
    rear = capacity - 1;
    array = new int[this.capacity];
  }

  // Queue is full when size becomes
  // equal to the capacity
  boolean isFull (Queue queue)
  {
    return (queue.size == queue.capacity);
  }

  // Queue is empty when size is 0
  boolean isEmpty (Queue queue)
  {
    return (queue.size == 0);
  }

  // Method to add an item to the queue.
  // It changes rear and size
  void enqueue (int item)
  {
    if (isFull (this))
      return;
    this.rear = (this.rear + 1) % this.capacity;
    this.array[this.rear] = item;
    this.size = this.size + 1;

  }
  int dequeue ()
  {
    if (isEmpty (this))
      return Integer.MIN_VALUE;

    int item = this.array[this.front];
    this.front = (this.front + 1) % this.capacity;
    this.size = this.size - 1;
    return item;
  }



  public Queue queuereverse (Queue q)
  {
    Stack < Integer > stk = new Stack <> ();
    while (!q.isEmpty (q))
      {
	stk.add (q.array[front]);
	q.dequeue ();
      }
    while (!stk.isEmpty ())
      {
	q.enqueue (stk.peek ());
	stk.pop ();
      }
    return q;
  }

  public void disp () /* function to display the elements of the queue */
  {

    if (front == -1)
      {
	System.out.print ("\nQueue is Empty");
      }
    else
      {
	for (int i = front; i <= rear; i++)
	  {
	    System.out.print (array[i] + "  ");
	  }
      }
    System.out.println ();
  }

}

// Driver class
public class Main
{
  public static void main (String[]args)
  {
    Queue queue = new Queue (1000);

      queue.enqueue (10);
      queue.enqueue (20);
      queue.enqueue (30);
      queue.enqueue (40);

      System.out.println ("Original queue : ");
      queue.disp ();
      System.out.println ();

      queue = queue.queuereverse (queue);

      System.out.println ("Queue after reversing : ");
      queue.disp ();

      System.out.println ();


  }
}

Output: 
Original queue : 
10  20  30  40  

Queue after reversing : 
40  30  20  10

import java.util.*;

// Java program to reverse a queue
public class Main
{



  //function to print the queue
  static void disp (Queue q) /* function to display the elements of the queue */
  {

    if (q.isEmpty ())
      {
	System.out.print ("\nQueue is Empty");
      }
    else
      {

	while (!q.isEmpty ())
	  {
	    System.out.print (" " + q.peek ());
	    q.remove ();
	  }
      }
    System.out.println ();
  }

  // Function to reverse the queue using stack
  static void reversequeue (Queue q)
  {

    Stack < Integer > stack = new Stack <> ();
    while (!q.isEmpty ())
      {
	stack.add ((Integer) q.peek ());
	q.remove ();
      }
    while (!stack.isEmpty ())
      {
	q.add (stack.peek ());
	stack.pop ();
      }
  }


  public static void main (String args[])
  {
    Queue < Integer > queue;
    queue = new LinkedList < Integer > ();
    queue.add (10);
    queue.add (20);
    queue.add (30);
    queue.add (40);

    reversequeue (queue);
    System.out.println ("Queue after reversing :");
    disp (queue);
  }
}

Output: 
Queue after reversing :
 40 30 20 10