Doubly linked list implementation

A doubly-linked list is a linked data structure that consists of a set of sequentially linked records called nodes. Each node contains two fields, called links, that are references to the previous and to the next node in the sequence of nodes. The beginning and ending nodes previous and next links, respectively, point to some kind of terminator, typically a sentinel node or null, to facilitate traversal of the list. If there is only one sentinel node, then the list is circularly linked via the sentinel node. It can be conceptualized as two singly linked lists formed from the same data items, but in opposite sequential orders.

Here is the pictorial view of doubly linked list:

The two node links allow traversal of the list in either direction. While adding or removing a node in a doubly-linked list requires changing more links than the same operations on a singly linked list, the operations are simpler and potentially more efficient, because there is no need to keep track of the previous node during traversal or no need to traverse the list to find the previous node, so that its link can be modified.

Here is the pictorial view of inserting an element in the middle of a doubly linked list:

Here is the pictorial view of deleting an element in the middle of a doubly linked list:

Below shows the java implementation of doubly linked list:

adding: 10
adding: 34
adding: 56
adding: 364
iterating forward..
deleted: 34
deleted: 364
iterating backword..