List.java

/**
* List interface 
 * @author Wei Zhong Tee
 * @since 8 May 2020
 */
public interface List<E> {

  /** Remove all contents from the list, so it is once again
      empty. */
  public void clear();



  /** Insert an element at the given location.
	* allows you to insert after the tail
    * @param item The element to be inserted.
	*/
    public void insert(int index, E item);


  /** Append an element at the end of the list.
   *  @param item The element to be appended.
   */
  public void add(E item);


  /**
  * Remove the  element at the given location.
  */
  public void remove(int index);



  /**
  * Get the element in the position to one step left.
  * @return element in the node to the left of the node at the index,
  * null if at the head.
  */
  public E prev(int index);


  /** Get the element in the position one step right.
  * @return the element in the node to the right of
  * the node at the index, null if at the end.
  */
  public E next(int index);


  /** @return The number of elements in the list. */
  public int length();


   /** Turn the contents of the Nodes to a string in order from head to end.
   * @return The String representation of the
   * elements in the list from head to end.
   */
   public String toString();

   /** Reverse the content of the list.
	* if list is A => B => C it becomes C => B => A
	*/
  public void reverse();


   /** @return The  element at given position. */
   public E getValue(int index);


}