Constructor Detail

• DoublyLinkedList

  public DoublyLinkedList()

  Constructs a new empty list.

Method Detail

• size

  public int size()

  Returns the number of elements in the linked list.

  Returns:

  number of elements in the linked list

• isEmpty

  public boolean isEmpty()

  Tests whether the linked list is empty.

  Returns:

  true if the linked list is empty, false otherwise

• first

  public E first()

  Returns (but does not remove) the first element of the list.

  Returns:

  element at the front of the list (or null if empty)

• last

  public E last()

  Returns (but does not remove) the last element of the list.

  Returns:

  element at the end of the list (or null if empty)

• addFirst

  public void addFirst(E e)

  Adds an element to the front of the list.

  Parameters:

  e - the new element to add

• addLast

  public void addLast(E e)

  Adds an element to the end of the list.

  Parameters:

  e - the new element to add

• removeFirst

  public E removeFirst()

  Removes and returns the first element of the list.

  Returns:

  the removed element (or null if empty)

• removeLast

  public E removeLast()

  Removes and returns the last element of the list.

  Returns:

  the removed element (or null if empty)

• toString

  public String toString()

  Produces a string representation of the contents of the list. This exists for debugging purposes only.

  Overrides:

  toString in class Object