import java.util.Vector;
import Student;

/**
 * A list of students enrolled in a particular course.  Developed as
 * an illustration of a use of vectors.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of January 1999
 */
public class ClassList {
  // +--------+--------------------------------------------------
  // | Fields |
  // +--------+

  /** The members of the class.  */
  protected Vector members;

  /** The name of the class.  */
  protected String name;


  // +--------------+--------------------------------------------
  // | Constructors |
  // +--------------+

  /**
   * Build a new class list, specifying the name of the class.
   */
  public ClassList(String name) {
    this.name = name;
    this.members = new Vector();
  } // ClassList(String)


  // +-----------+-----------------------------------------------
  // | Modifiers |
  // +-----------+

  /**
   * Add a student to the class list.  Does not add a student
   * who is already in the class.
   */
  public void addStudent(Student student) {
    if (this.members.contains(student)) {
      // Already in the class, do nothing.
    }
    else {
      this.members.addElement(student);
    }
  } // addStudent(Student)

  /**
   * Remove a student from the class.  
   */
  public void removeStudent(Student student) {
    this.members.removeElement(student);
  } // removeStudent(Student)

  /**
   * Set the grade of a student in the class.
   */
  public void setGrade(Student student, int grade) {
    // Look up the index of the student.
    int index = this.members.indexOf(student);
    // Declare a member of the class.
    Student member;

    // Did we find the student?
    if (index != -1) {
      member = (Student) this.members.elementAt(index);
      member.setGrade(grade);
    } // if the student is in the class
  } // setGrade(Student, int)


  // +------------+----------------------------------------------
  // | Extractors |
  // +------------+

  /**
   * Get the grade assigned to a particular student.  Returns
   * -1 if there is no such student in the class.
   */
  public int getGrade(Student student) {
    // Look up the index of the student.
    int index = this.members.indexOf(student);
    // Declare a member of the class.
    Student member;

    // Did we find the student?
    if (index != -1) {
      member = (Student) this.members.elementAt(index);
      return member.getGrade();
    } // if the student is in the class
    else { // the student is not in the class
      return -1;
    } // the student is not in the class
  } // getGrade(Student)

  /**
   * Generate a string listing the members of the class.
   */
  public String toString() {
    return this.name + ": " + this.members.toString();
  } // toString()

} // class ClassList