Notes

public class Main {
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 deleteNode(Node del)
{

if (head == null || del == null) {
return;
}


if (head == del) {
head = del.next;
}

if (del.next != null) {
del.next.prev = del.prev;
}

if (del.prev != null) {
del.prev.next = del.next;
}

return;
}
public void printlist(Node node)
{
Node last = null;
System.out.println("Traversal in forward Direction");
while (node != null) {
System.out.print(node.data + " ");
last = node;
node = node.next;
}
System.out.println();
System.out.println("Traversal in reverse direction");
while (last != null) {
System.out.print(last.data + " ");
last = last.prev;
}
}


public static void main(String[] args)
{

Main m = new Main();

m.push(7);


m.push(1);

m.InsertAfter(m.head.next, 8);


System.out.println("Created DLL is: ");
m.printlist(m.head);

m.deleteNode(m.head);

System.out.print("nList after deleting first node: ");
m.printlist(m.head);

m.deleteNode(m.head.next);

System.out.print("nList after Deleting middle node: ");
m.printlist(m.head);
}
}