queuebyll.java

public class queuebyll {
   static class Node{
        int data;
        Node next;
        
        Node(int data){
            this.data=data;
            this.next=null;
        }
    }
    static class Queue{
        static Node head=null;
        static Node tail=null;
        public static boolean isEmpty(){
            return head==null && tail==null;
        }
        public static void add(int data){
            Node newNode=new Node(data);
            if(tail==null){
                tail=head=newNode;
            }
          
          tail.next=newNode;
          tail=newNode;

        }
        public static int remove(){
            if(isEmpty()) return -1;
            if(head==tail){
                tail=null;
            }
            int front=head.data;
            head=head.next;

            return front;

        }
        public static int peek(){
            if(isEmpty()) return -1;
        return head.data;        }
    }
    public static void main(String[] args) {
        Queue q=new Queue();
        q.add(1);
        q.add(2);
        q.add(3);
        q.add(4);
        q.add(5);
        
        while(!q.isEmpty())
{
    System.out.println(q.peek());
    q.remove();
}    }
}