Public void addData (int index, T newData) throws InvalidPositionException. This method must add a new node to the list storing newData. The node must be inserted in the index position of the list. Therefore, if index = 0 then the new node must be inserted at the beginning of the list. If index = 1, the new node is added after the first node in the list; if index = 2, then the new node is added after the second node of the list, and so on. If index = numDataItems, then the new node is added to the end of the list. If index < 0 or index > numDataItems an InvalidPositionException must be thrown.

DoubleList()

  {

      numElements=0;

      front=rear=null;

  }

  public void addData(int index,T newData) throws InvalidPositionException

  {

      if(index<0||index>numElements)

          throw new InvalidPositionException();

      DoubleNode newNode=new DoubleNode(newData);

      numElements++;

      // if there is no node initially

      if(front==null)

      {

          front=rear=newNode;

          return;

      }

      // get the node after which we have to add the new node

      DoubleNode pre=null,temp=front;

      while(temp!=null&&index>0)

      {

          pre=temp;

          temp=temp.next;

          index--;

      }

      if(pre==null)

      {

          newNode.next=front;

          front.previous=newNode;

          front=newNode;

      }

      else

      {

          newNode.next=temp;

          newNode.previous=pre;

          pre.next=newNode;

      }

  }

  public DoubleNode<T> getNode(int index)

  {

      if(index<0||index>=numElements)

          try {

              throw new InvalidPositionException();

          } catch (InvalidPositionException e) {

              // TODO Auto-generated catch block

              e.printStackTrace();

          }

      DoubleNode temp=front;

      // traverse the list till we reach at the given index and return the address of that node

      while(temp!=null&&index>0)

      {

          temp=temp.next;

          index--;

      }

      return temp;

  }

  public void removeData(int index) throws InvalidPositionException

  {

      DoubleNode temp;

      temp = getNode(index); // get the reference to the node at the given index

      numElements--;

      // if there is only one node in the linkedlist then after removing there is no node

      if(numElements==0)

      {

          front=rear=null;

      }

      else

      {

          temp.previous.next=temp.next;

          if(temp.next!=null)

              temp.next.previous=temp.previous;

      }

  }

  public T getData(int index) throws InvalidPositionException

  {

      DoubleNode temp=null;

      temp = getNode(index); // get the Node from where we have to get the data

      return (T) temp.data;

  }

  public void setData(int index ,T newData) throws InvalidPositionException

  {

      DoubleNode temp;

      temp = getNode(index); // get the node where we have to set the newData

      temp.data=newData;

  }

Explanation:

See the complete code in answer section.