import java.util.Scanner;
   import java.io.*;
   import javax.swing.JOptionPane;
	
    public class DoubleLinked
   {
       public static void main(String[] args) throws FileNotFoundException
      {
			DLNode head=new DLNode("",null,null);
			insert(head,"A");
			insert(head,"B");
			insert(head,"C");
			insert(head,"D");
			print(head);
	   }
   	
   	public static void print(DLNode head)
   	{
   		System.out.print("[");
         while(head != null)
         {	
				System.out.print(head.getValue());
				if(head.getPrev()!=null)
					System.out.print(", ");
            head = head.getPrev();
		   }
         System.out.println("]");
   	}

       public static void insert(DLNode t, Object obj)
      {
         if(t==null)
            {	
            	t = new DLNode(obj, null, null);
         	}
         else if(t.getNext()==null)
         {	
				System.out.print("FME2 "+obj);
         	t.setNext(new DLNode(obj,t,null));
			}
         else
         {
				System.out.print("FME3 "+obj);
            DLNode cool=new DLNode(obj,t,t.getNext());
    			t.getNext().setPrev(cool);	        
				t.setNext(cool);
         }
      }
   	
       public static void remove(DLNode t)
      {
         if(t.getPrev()==null)
            t.getNext().setPrev(null);
         else if(t.getNext()==null)
            t.getPrev().setNext(null);
         else
         {
            t.getPrev().setNext(t.getNext());
            t.getNext().setPrev(t.getPrev());
         }
      }
   	
   }