import java.util.Iterator;

/**
 * Specifies an abstract data type for a completely unordered collection of
 * generic objects that is not permitted to contain any duplicated elements, as
 * defined by the generic object's equals method.
 *
 * @author Lewis & Chase ISBN 0-321-24584-9 Ch03
 * @version 2011-09-15 by D.P. Daugherty
 *
 */
public interface SetADT<T> {

    /**
     * Adds one element to the set, but only if an equal element is not already
     * contained therein.
     *
     * @param element
     *            the element to be added
     */
    public void add(T element);

    /**
     * Removes and returns a randomly selected element from the set and adjusts
     * the set size accordingly
     *
     * @return the element which has been removed from the set
     * @throws EmptySetException
     */
    public T removeRandom();

    /**
     * Removes the specified element if it is present in the set, otherwise
     * makes no changes
     *
     * @param element
     */
    public void remove(T element);

    /**
     * Combines the elements of two sets into a third new set with no duplicates
     * permitted
     *
     * @param set
     *            the set to be combined with this set
     * @return a new set that contains the union of the two sets being combined
     */
    public SetADT<T> union(SetADT<T> set);

    /**
     * Checks to see if an element is already contained in the set
     *
     * @param element
     *            the element to be checked for containment
     * @return true if element is contained in the set, false otherwise
     */
    public boolean contains(T element);

    /**
     * Check to see if two sets are exactly equal, ignoring order of the
     * elements
     *
     * @param set
     *            the set to be checked for equality
     * @return true if two sets contain exactly the same elements
     */
    public boolean equals(SetADT<T> set);

    /**
     * Check to see if set contains no elements
     *
     * @return true if set has no elements, false otherwise
     */
    public boolean isEmpty();

    /**
     * Returns the number of distinct elements in the set
     *
     * @return count of distinct elements
     */
    public int size();

    public Iterator<T> iterator();

    /**
     * Returns a list of elements in the set separated by commas and enclosed in
     * square brackets
     *
     * @return a string describing the contents of the set
     */
    public String toString();
}