public class DoubleLinked { 
    Node head; 
  
    class Node { 
        int data; 
        Node prev; 
        Node next; 

        Node(int d) { data = d; } 
    } 

    public void push(int new_data) 
    { 

        Node new_Node = new Node(new_data); 
  
        new_Node.next = head; 
        new_Node.prev = null; 
  
        if (head != null) 
            head.prev = new_Node; 
  
        head = new_Node; 
    } 

    public void InsertAfter(Node prev_Node, int new_data) 
    { 

        if (prev_Node == null) { 
            System.out.println("The given previous node cannot be NULL "); 
            return; 
        } 
  
        Node new_node = new Node(new_data); 

        new_node.next = prev_Node.next; 

        prev_Node.next = new_node; 
  
        new_node.prev = prev_Node; 

        if (new_node.next != null) 
            new_node.next.prev = new_node; 
    } 
  
    void append(int new_data) 
    { 

        Node new_node = new Node(new_data); 
  
        Node last = head; 
  
        new_node.next = null; 
  

        if (head == null) { 
            new_node.prev = null; 
            head = new_node; 
            return; 
        } 

        while (last.next != null) 
            last = last.next; 
  
        last.next = new_node; 
 
        new_node.prev = last; 
    } 
  
    public void printlist(Node node) 
    { 
        Node last = null; 
        System.out.println("List Traversal dari depan : "); 
        while (node != null) { 
            System.out.print(node.data + " "); 
            last = node; 
            node = node.next; 
        } 
        System.out.println(); 
        System.out.println("List Traversal dari belakang : "); 
        while (last != null) { 
            System.out.print(last.data + " "); 
            last = last.prev; 
        } 
    } 
    public static void main(String[] args) 
    { 
        DoubleLinked dll = new DoubleLinked(); 
        dll.append(6); 
        dll.push(7);  
        dll.push(1); 
        dll.append(4); 
        dll.InsertAfter(dll.head.next, 8); 
  
        System.out.println("Created DLL is: "); 
        dll.printlist(dll.head); 
    } 
}