public class Queue_byCircularArray {

static class Queue{

static int arr[];

static int size;

static int rear = -1;

static int front = -1;

Queue(int n){

arr = new int[n];

this.size = n;

}

public static boolean isEmpty(){

return rear == -1 && front == -1;

}

public static boolean isFull(){

return (rear+1)%size == front;

}

public static void add(int data){

if(isFull()){

System.out.println("full queue");

return;

}

// for adding very first element

if(front == -1)

front = 0;

rear = (rear+1)%size;

arr[rear] = data;

}

public static int remove(){

if (isEmpty()){

System.out.println("empty queue");

return -1;

}

int result = arr[front];

// single element condition

if(rear == front) {rear=front=-1;}

else {front = (front+1)%size;}

return result;

}

public static int peek(){

if(isEmpty()){

System.out.println("empty queue");

return -1;

}

return arr[front];

}

}

public static void main(String[] args) {

Queue q = new Queue(5);

q.add(0);

q.add(1);

q.add(2);

q.add(3);

//q.remove();

while(!q.isEmpty()){

System.out.println(q.peek());

q.remove();

}

}

}