_101circularqueue.java

public class _101circularqueue {
    static class Queue{
        static int arr[];
        static int size;
        static int rear;
        static int front;
        Queue(int n){
            arr = new int[n];
            size = n;
            rear = -1;
            front = -1;
        }
        public static boolean isEmpty(){
            return rear==-1;
        }
        public static boolean isFull(){
            return (rear+1)%size == front;
        }
        public static void add(int data){
            if(isFull()){
                System.out.println("Queue is full");
                return;
            }
            if(front==-1){
                front= 0;
            }
            rear= (rear+1%size);
            arr[rear] = data;
        }
        public static int remove(){
            if(isEmpty()){
                System.out.println("Queue is Empty");
                return -1;
            }
            int result = arr[front];
            if(rear == front){
                rear=front=-1;
            } else{
                front=(front+1)%size;
            }   
            return front;
        }
        public static int peek(){
            if(isEmpty()){
                System.out.println("Queue is empty");
                return -1;
            }
            return arr[front];
        }
    }
    public static void main(String[] args) {
        Queue q = new Queue(5);
        q.add(1);
        q.add(2);
        q.add(3);
        while(!q.isEmpty()){
            System.out.println(q.peek());
            q.remove();
        }
    }
}