In a constructor create a node headnexthead headprevhead my

In a constructor create a node head-next=head head-prev=head my head-next=head-next my node-prev=head head-next-prev=my node head-next=my node

Solution

public boolean add(E element) { LLNode newNode = new LLNode (element); if (element == null) { throw new NullPointerException(\"Element can not store a null reference!\"); } else { newNode.next = tail; // set new.next to tail newNode.prev = tail.prev; // set new.prev to prior last tail.prev.next = newNode; // set prior last.next to new last tail.prev = newNode; // set tail.prev to new last size++; } return true; }