// ********************************************************
// Interface IntegerListInterface for the ADT list.
// *********************************************************
public interface IntegerListInterface {
   public boolean isEmpty();
   // Determines whether a list is empty.
   // Precondition: None.
   // Postcondition: Returns true if the list is empty,
   // otherwise returns false.
   // Throws: None.

   public int size();
   // Determines the length of a list.
   // Precondition: None.
   // Postcondition: Returns the number of items that are
   // currently in the list.
   // Throws: None.

   public void removeAll();
   // Deletes all the items from the list.
   // Precondition: None.
   // Postcondition: The list is empty.
   // Throws: None.
   public void add(int index, int item) 
            throws ListIndexOutOfBoundsException,
                   ListException;
   // Adds an item to the list at position index.
   // Precondition: index indicates the position at which  
   // the item should be inserted in the list.
   // Postcondition: If insertion is successful, item is 
   // at position index in the list, and other items are
   // renumbered accordingly.
   // Throws: ListIndexOutOfBoundsException if index < 1 or 
   // index > size()+1.
   // Throws: ListException if item cannot be placed on 
   // the list.

   public int get(int index) throws
         ListIndexOutOfBoundsException;
   // Retrieves a list item by position.
   // Precondition: index is the number of the item to be
   // retrieved.
   // Postcondition: If 1 <= index <= size(), the item at
   // position index in the list is returned.
   // Throws: ListIndexOutOfBoundsException if index < 1 or 
   // index > size().

   public void remove(int index) 
               throws ListIndexOutOfBoundsException;
   // Deletes an item from the list at a given position.
   // Precondition: index indicates where the deletion 
   // should occur. 
   // Postcondition: If 1 <= index <= size(), the item at 
   // position index in the list is deleted, and other items
   // are renumbered accordingly.
   // Throws: ListIndexOutOfBoundsException if index < 1 or 
   // index > size().

} // end IntegerListInterface