Program for Double Linked list

This program helps us in how to develop Double Linked list

class DoubleMain 
{
 public static void main(String[] args) 
 {
  DoubleLink obj=new DoubleLink();
  obj.insert(4);
  obj.insert(5);
  obj.insert(6);
  obj.insert(7);
  obj.front();
  System.out.println("FRONT DIRECTION ");
  obj.insertAtFirst(8);
  obj.front();
  System.out.println("BACK DIRECTION ");
  obj.back();
 }
}



class DoubleLink 
{
 Node head=null,prev=null,curr=null;
 void insert(int item)
 {
  
  Node data=new Node(item);
  if(head==null)
  {
   head=data;
   curr=head;
   prev=head;
  } 
  else
  {
   curr.next=data;
   curr=data;
   data.previous=prev;
   prev=data;
  }
 }
 public void front()
 {
  curr=head;
  while(curr!=null)
  {
   System.out.println(curr.data);
   curr=curr.next;
  }
 }
 public void back()
 {
  curr=prev;
  while(curr!=null)
  {
   System.out.println(curr.data);
   curr=curr.previous;
  }
 }
 public void insertAtFirst(int item)
 {
  Node data=new Node(item);
  data.next=head;
  head.previous=data;
  head=data;
 }
}