/** An interface for the ADT list.
* Entries in the list have positions that begin with 1.
*/
public interface ListInterface < T >
{
    /** Task: Adds a new entry to the end of the list.
    * Entries currently in the list are unaffected.
    * The lists size is increased by 1.
    * @param newEntry the object to be added as a new entry
    * @return true if the addition is successful, or false if the list
    * is full */

    public boolean add (T newEntry);
    /** Task: Adds a new entry at a specified position within the list.
    * Entries originally at and above the specified position
    * are at the next higher position within the list.
    * The lists size is increased by 1.
    * @param newPosition an integer that specifies the desired
    * position of the new entry
    * @param newEntry the object to be added as a new entry
    * @return true if the addition is successful, or
    * false if either the list is full, newPosition < 1, or
    * newPosition > getLength()+1 */

    public boolean add (int newPosition, T newEntry);
    /** Task: Removes the entry at a given position from the list.
    * Entries originally at positions higher than the given
    * position are at the next lower position within the list,
    * and the lists size is decreased by 1.
    * @param givenPosition an integer that indicates the position of
    * the entry to be removed
    * @return a reference to the removed entry or null, if either
    * the list was empty, givenPosition < 1, or
    * givenPosition > getLength() */

    public T remove (int givenPosition);
    /** Task: Removes all entries from the list. */

    public void clear ();
    /** Task: Replaces the entry at a given position in the list.
    * @param givenPosition an integer that indicates the position of the
    * entry to be replaced
    * @param newEntry the object that will replace the entry at the
    * position givenPosition
    * @return true if the replacement occurs, or false if either the
    * list is empty, givenPosition < 1, or
    * givenPosition > getLength() */

    public boolean replace (int givenPosition, T newEntry);
    /** Task: Retrieves the entry at a given position in the list.
    * @param givenPosition an integer that indicates the position of
    * the desired entry
    * @return a reference to the indicated entry or null, if either
    * the list is empty, givenPosition < 1, or
    * givenPosition > getLength() */

    public T getEntry (int givenPosition);
    
    /** Task: Reverses the order of the items in the list. */

    public void reverse ( );
    /** Task: Sees whether the list contains a given entry.
    * @param anEntry the object that is the desired entry
    * @return true if the list contains anEntry, or false if not */

    public boolean contains (T anEntry);
    /** Task: Gets the length of the list.
    * @return the integer number of entries currently in the list */

    public int getLength ();
    /** Task: Sees whether the list is empty.
    * @return true if the list is empty, or false if not */

    public boolean isEmpty ();
    /** Task: Sees whether the list is full.
    * @return true if the list is full, or false if not */

    public boolean isFull ();
    /** Task: Displays all entries that are in the list, one per line,
    * in the order in which they occur in the list. */

    public void display ();

} // end ListInterface