CircularDoublyLinkedList.java

package circularLinkedList;

import java.util.*;

/*  Class Node  */
	class Node
	{
	    protected double data;
	    protected Node next, prev;
	 
	    /* Constructor */
	    public Node()
	    {
	        next = null;
	        prev = null;
	        data = 0;
	    }
	    /* Constructor */
	    public Node(double data, Node next, Node prev)
	    {
	        this.data = data;
	        this.next = next;
	        this.prev = prev;
	    }
	    /* Function to set link to next node */
	    public void setLinkNext(Node n)
	    {
	        next = n;
	    }
	    /* Function to set link to previous node */
	    public void setLinkPrev(Node p)
	    {
	        prev = p;
	    }    
	    /* Function to get link to next node */
	    public Node getLinkNext()
	    {
	        return next;
	    }
	    /* Function to get link to previous node */
	    public Node getLinkPrev()
	    {
	        return prev;
	    }
	    /* Function to set data to node */
	    public void setData(double d)
	    {
	        data = d;
	    }
	    /* Function to get data from node */
	    public double getData()
	    {
	        return data;
	    }
	}
	 
	/* Class linkedList */
	class linkedList
	{
	    protected Node start;
	    protected Node end ;
	    public int size;
	 
	    /* Constructor */
	    public linkedList()
	    {
	        start = null;
	        end = null;
	        size = 0;
	    }
	    
	    
	    /*Function to insert element  */
	    public void insert(double d)
	    {
	        Node nptr = new Node(d, null, null);        
	        if (start == null)
	        {
	            nptr.setLinkNext(nptr);
	            nptr.setLinkPrev(nptr);
	            start = nptr;
	            end = start;
	        }
	        else
	        {
	            nptr.setLinkPrev(end);
	            end.setLinkNext(nptr);
	            start.setLinkPrev(nptr);
	            nptr.setLinkNext(start);
	            end = nptr;    
	        }
	        size++;
	    }
	    
	    /* Function to display status of list */
	    public void display()
	    {
	        System.out.print("\nCircular Doubly Linked List = ");
	        Node ptr = start;
	        if (size == 0) 
	        {
	            System.out.print("empty\n");
	            return;
	        }
	        if (start.getLinkNext() == start) 
	        {
	            System.out.print(start.getData()+ " <-> "+ptr.getData()+ "\n");
	            return;
	        }
	        System.out.print(start.getData()+ " <-> ");
	        ptr = start.getLinkNext();
	        while (ptr.getLinkNext() != start) 
	        {
	            System.out.print(ptr.getData()+ " <-> ");
	            ptr = ptr.getLinkNext();
	        }
	        System.out.print(ptr.getData()+ " <-> ");
	        ptr = ptr.getLinkNext();
	        System.out.print(ptr.getData()+ "\n");
	    }
		public Iterator<Integer> Iterator()
		{
			
			return null;
		}
	}
	 
	/* Class CircularDoublyLinkedList */
	public class CircularDoublyLinkedList
	{    
	    public static void main(String[] args)
	    {
			Scanner scan = new Scanner(System.in);
	        
	        /* Creating object of linkedList */
	        linkedList list = new linkedList();
	        
	        /* Number of Node */
	        System.out.println("Enter the Number of Nodes");
	        int n = scan.nextInt();
	        
	        /*  Perform list operations  */
	       for(int i=1; i<=n; i++)
	       {
	        	try
	        	{
	        	System.out.println("Enter the Node");
		             list.insert( scan.nextDouble() );  
	        	} 
	        	catch (InputMismatchException e) 
	        	{
					list.display();
					System.exit(0); 
	        	}
	      	 }     
	       		
	        /* For Displaying the List*/
	             list.display();
	             
	       	/* Scanner Close*/
	       		scan.close();
	    }
}