package rebelsky.student;

import java.util.Comparator;

/**
 * A mechanism for comparing students to each other.  The
 * student who comes "alphabetically first" is considered
 * to come first.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of October 2004.
 */
public class CompareStudentsByName
	implements Comparator
{
	/**
	 * Determine if alpha comes alphabetically before beta.
	 * One student comes alphabetically before another student
	 * if (a) the last name of the student is alphabetically
	 * smaller or (b) the last names are the same and the first
	 * name of the student is smaller.
	 *
	 * @param alpha  a Student to be compared
	 * @param beta  a Student to be compared
	 * @return
	 *   (a) a negative number if alpha comes before beta;
	 *   (b) a positive number if alpha comes after beta;
	 *   (c) zero, if the two have the same first and last names
	 * @exception ClassCastException
	 *   if either parameter is not a student
	 */
	public int compare(Object alpha, Object beta)
	{
		// Convert the two values to students.
		Student sa = (Student) alpha;
		Student sb = (Student) beta;
		// Get last names and use string comparison
		return sa.getName().compareTo(sb.getName());
	} // compare(Object, Object)
} // CompareStudentsByName