package dataStructures1112;

import java.io.Serializable;

public interface List<E> extends Serializable
{

    // Returns true iff the list contains no elements.
    boolean isEmpty( );

    // Returns the number of elements in the list.
    int size( );

    // Returns an iterator of the elements in the list (in proper sequence).
    Iterator<E> iterator( );

    // Returns the first element of the list.
    E getFirst( ) throws EmptyListException;

    // Returns the last element of the list.
    E getLast( ) throws EmptyListException;
 
    // Returns the element at the specified position in the list.
    // Range of valid positions: 0, ..., size()-1.
    // If the specified position is 0, get corresponds to getFirst. 
    // If the specified position is size()-1, get corresponds to getLast.    
    E get( int position ) throws InvalidPositionException;

    // Returns the position of the first occurrence of the specified element
    // in the list, if the list contains the element.
    // Otherwise, returns -1.
    int find( E element );

    // Inserts the specified element at the first position in the list.
    void addFirst( E element );

    // Inserts the specified element at the last position in the list.
    void addLast( E element );

    // Inserts the specified element at the specified position in the list.
    // Range of valid positions: 0, ..., size(). 
    // If the specified position is 0, add corresponds to addFirst.
    // If the specified position is size(), add corresponds to addLast.
    void add( int position, E element ) throws InvalidPositionException;

    // Removes and returns the element at the first position in the list.
    E removeFirst( ) throws EmptyListException;

    // Removes and returns the element at the last position in the list.
    E removeLast( ) throws EmptyListException;

    // Removes and returns the element at the specified position in the list.
    // Range of valid positions: 0, ..., size()-1.
    // If the specified position is 0, remove corresponds to removeFirst. 
    // If the specified position is size()-1, remove corresponds to removeLast.
    E remove( int position ) throws InvalidPositionException;

    // Removes the first occurrence of the specified element from the list
    // and returns true, if the list contains the element.
    // Otherwise, returns false.
    boolean remove( E element );

}