deleteEnd.java

public class DeleteEnd 
{  
    //Represents the node of list.  
    public class Node{  
        int data;  
        Node next;  
        public Node(int data) 
        {  
            this.data = data;  
        }  
    }  
  
    //Declaring head and tail pointer as null.  
    public Node head = null;  
    public Node tail = null;  
  
    //This function will add the new node at the end of the list.  
    public void add(int data)
    {  
        //Create new node  
        Node newNode = new Node(data);  
        //Checks if the list is empty.  
        if(head == null) 
        {  
             //If list is empty, both head and tail would point to new node.  
            head = newNode;  
            tail = newNode;  
            newNode.next = head;  
        }  
        else 
        {  
            //tail will point to new node.  
            tail.next = newNode;  
            //New node will become new tail.  
            tail = newNode;  
            //Since, it is circular linked list tail will point to head.  
            tail.next = head;  
        }  
    }  
  
    //Deletes node from end of the list  
    public void deleteEnd() 
    {  
        //Checks whether list is empty  
        if(head == null) 
        {  
            return;  
        }  
        else {  
            //Checks whether contain only one element  
            if(head != tail ) 
            {  
                Node current = head;  
                //Loop will iterate till the second last element as current.next is pointing to tail  
                while(current.next != tail) 
                {  
                    current = current.next;  
                }  
                //Second last element will be new tail  
                tail = current;  
                //Tail will point to head as it is a circular linked list  
                tail.next = head;  
            }  
            //If the list contains only one element  
            //Then it will remove it and both head and tail will point to null  
            else 
            {  
                head = tail = null;  
            }  
        }  
    }  
  
    //Displays all the nodes in the list  
    public void display() 
    {  
        Node current = head;  
        if(head == null) 
        {  
            System.out.println("List is empty");  
        }  
        else 
        {  
             do
             {  
                //Prints each node by incrementing pointer.  
                System.out.print(" "+ current.data);  
                current = current.next;  
            }while(current != head);  
            System.out.println();  
        }  
    }  
  
    public static void main(String[] args) 
    {  
        DeleteEnd cl = new DeleteEnd();  
        //Adds data to the list  
        cl.add(1);  
        cl.add(2);  
        cl.add(3);  
        cl.add(4);  
        //Printing original list  
        System.out.println("Original List: ");  
        cl.display();  
        while(cl.head != null) 
        {  
            cl.deleteEnd();  
            //Printing updated list  
            System.out.println("Updated List: ");  
            cl.display();  
        }  
    }  
}