import java.util.*;

// Class for queue

class Queue

{

private int arr[]; // array to store queue elements

private int front; // front points to front element in the queue

private int rear; // rear points to last element in the queue

private int capacity; // maximum capacity of the queue

private int count; // current size of the queue

// Constructor to initialize queue

Queue(int size)

{

arr = new int[size];

capacity = size;

front = 0;

rear = -1;

count = 0;

}

// Utility function to remove front element from the queue

public void dequeue()

{

// check for queue underflow

if (isEmpty())

{

System.out.println("UnderFlow\nProgram Terminated");

System.exit(1);

}

System.out.println("Removing " + arr[front]);

front = (front + 1) % capacity;

count--;

}

// Utility function to add an item to the queue

public void enqueue(int item)

{

// check for queue overflow

if (isFull())

{

System.out.println("OverFlow\nProgram Terminated");

System.exit(1);

}

System.out.println("Inserting " + item);

rear = (rear + 1) % capacity;

arr[rear] = item;

count++;

}

// Utility function to return front element in the queue

public int peek()

{

if (isEmpty())

{

System.out.println("UnderFlow\nProgram Terminated");

System.exit(1);

}

return arr[front];

}

// Utility function to return the size of the queue

public int size()

{

return count;

}

// Utility function to check if the queue is empty or not

public Boolean isEmpty()

{

return (size() == 0);

}

// Utility function to check if the queue is empty or not

public Boolean isFull()

{

return (size() == capacity);

}

// Queue implementation in java

public static void main (String[] args)

{

// create a queue of capacity 5

Queue q = new Queue(5);

q.enqueue(1);

q.enqueue(2);

q.enqueue(3);

System.out.println("Front element is: " + q.peek());

q.dequeue();

System.out.println("Front element is: " + q.peek());

System.out.println("Queue size is " + q.size());

q.dequeue();

q.dequeue();

if (q.isEmpty())

System.out.println("Queue Is Empty");

else

System.out.println("Queue Is Not Empty");

}

}

//SOURCE: https://www.techiedelight.com/queue-implementation-in-java/