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// Section.java - Chapter 16 version.
// Copyright 2000 by Jacquie Barker - all rights reserved.
// A MODEL class.
import java.util.*;
public class Section {
//------------
// Attributes.
//------------
private int sectionNo;
private char dayOfWeek;
private String timeOfDay;
private String room;
private int seatingCapacity;
private Course representedCourse;
private ScheduleOfClasses offeredIn;
private Professor instructor;
// The enrolledStudents Hashtable stores Student object references,
// using each Student's ssn as a String key.
private Hashtable enrolledStudents;
// The assignedGrades Hashtable stores TranscriptEntry object
// references, using a reference to the Student to whom it belongs
// as the key.
private Hashtable assignedGrades;
// We use PUBLIC STATIC int attributes to declare status codes
// that other classes can then inspect/interpret (see method
// reportStatus() in class SRS.java for an example of how these
// are used).
public static final int SUCCESSFULLY_ENROLLED = 0;
public static final int SECTION_FULL = 1;
public static final int PREREQ_NOT_SATISFIED = 2;
public static final int PREVIOUSLY_ENROLLED = 3;
//----------------
// Constructor(s).
//----------------
public Section(int sNo, char day, String time, Course course,
String room, int capacity) {
setSectionNo(sNo);
setDayOfWeek(day);
setTimeOfDay(time);
setRepresentedCourse(course);
setRoom(room);
setSeatingCapacity(capacity);
// A Professor has not yet been identified.
setInstructor(null);
// Note that we must instantiate empty hash tables.
enrolledStudents = new Hashtable();
assignedGrades = new Hashtable();
}
//-----------------
// Get/set methods.
//-----------------
public void setSectionNo(int no) {
sectionNo = no;
}
public int getSectionNo() {
return sectionNo;
}
public void setDayOfWeek(char day) {
dayOfWeek = day;
}
public char getDayOfWeek() {
return dayOfWeek;
}
public void setTimeOfDay(String time) {
timeOfDay = time;
}
public String getTimeOfDay() {
return timeOfDay;
}
public void setInstructor(Professor prof) {
instructor = prof;
}
public Professor getInstructor() {
return instructor;
}
public void setRepresentedCourse(Course c) {
representedCourse = c;
}
public Course getRepresentedCourse() {
return representedCourse;
}
public void setRoom(String r) {
room = r;
}
public String getRoom() {
return room;
}
public void setSeatingCapacity(int c) {
seatingCapacity = c;
}
public int getSeatingCapacity() {
return seatingCapacity;
}
public void setOfferedIn(ScheduleOfClasses soc) {
offeredIn = soc;
}
public ScheduleOfClasses getOfferedIn() {
return offeredIn;
}
//-----------------------------
// Miscellaneous other methods.
//-----------------------------
// For a Section, we want its String representation to look
// as follows:
//
// MATH101 - 1 - M - 8:00 AM
public String toString() {
return getRepresentedCourse().getCourseNo() + " - " +
getSectionNo() + " - " +
getDayOfWeek() + " - " +
getTimeOfDay();
}
// The full section number is a concatenation of the
// course no. and section no., separated by a hyphen;
// e.g., "ART101 - 1".
public String getFullSectionNo() {
return getRepresentedCourse().getCourseNo() +
" - " + getSectionNo();
}
public int enroll(Student s) {
// First, make sure that this Student is not already
// enrolled for this Section, and that he/she has
// NEVER taken and passed the course before.
Transcript transcript = s.getTranscript();
if (s.isCurrentlyEnrolledInSimilar(this) ||
transcript.verifyCompletion(this.getRepresentedCourse()))
return PREVIOUSLY_ENROLLED;
// If there are any prerequisites for this course,
// check to ensure that the Student has completed them.
Course c = getRepresentedCourse();
if (c.hasPrerequisites()) {
Enumeration e = c.getPrerequisites();
while (e.hasMoreElements()) {
Course pre = (Course) e.nextElement();
// See if the Student's Transcript reflects
// successful completion of the prerequisite.
if (!transcript.verifyCompletion(pre))
return PREREQ_NOT_SATISFIED;
}
}
// If the total enrollment is already at the
// the capacity for this Section, we reject this
// enrollment request.
if (!confirmSeatAvailability()) return SECTION_FULL;
// If we made it to here in the code, we're ready to
// officially enroll the Student.
// Note bidirectionality: this Section holds
// onto the Student via the Hashtable, and then
// the Student is given a handle on this Section.
enrolledStudents.put(s.getSsn(), s);
s.addSection(this);
return SUCCESSFULLY_ENROLLED;
}
// A private "housekeeping" method.
private boolean confirmSeatAvailability() {
if (enrolledStudents.size() < getSeatingCapacity())
return true;
else return false;
}
public boolean drop(Student s) {
// We may only drop a student if he/she is enrolled.
if (!s.isEnrolledIn(this)) return false;
else {
// Find the student in our Hashtable, and remove it.
enrolledStudents.remove(s.getSsn());
// Note bidirectionality.
s.dropSection(this);
return true;
}
}
public int getTotalEnrollment() {
return enrolledStudents.size();
}
// Used for testing purposes.
public void display() {
System.out.println("Section Information:");
System.out.println("\tSemester: " + getOfferedIn().getSemester());
System.out.println("\tCourse No.: " +
getRepresentedCourse().getCourseNo());
System.out.println("\tSection No: " + getSectionNo());
System.out.println("\tOffered: " + getDayOfWeek() +
" at " + getTimeOfDay());
System.out.println("\tIn Room: " + getRoom());
if (getInstructor() != null)
System.out.println("\tProfessor: " +
getInstructor().getName());
displayStudentRoster();
}
// Used for testing purposes.
public void displayStudentRoster() {
System.out.print("\tTotal of " + getTotalEnrollment() +
" students enrolled");
// How we punctuate the preceding message depends on
// how many students are enrolled (note that we used
// a print() vs. println() call above).
if (getTotalEnrollment() == 0) System.out.println(".");
else System.out.println(", as follows:");
// Use an Enumeration object to "walk through" the
// hash table.
Enumeration e = enrolledStudents.elements();
while (e.hasMoreElements()) {
Student s = (Student) e.nextElement();
System.out.println("\t\t" + s.getName());
}
}
// This method returns the value null if the Student has not
// been assigned a grade.
public String getGrade(Student s) {
// Retrieve the Student's transcript entry object, if one
// exists, and in turn retrieve its assigned grade.
TranscriptEntry te = (TranscriptEntry) assignedGrades.get(s);
if (te != null) {
String grade = te.getGrade();
return grade;
}
// If we found no TranscriptEntry for this Student, return
// a null value to signal this.
else return null;
}
public boolean postGrade(Student s, String grade) {
// Make sure that we haven't previously assigned a
// grade to this Student by looking in the Hashtable
// for an entry using this Student as the key. If
// we discover that a grade has already been assigned,
// we return a value of false to indicate that
// we are at risk of overwriting an existing grade.
// (A different method, eraseGrade(), can then be written
// to allow a Professor to change his/her mind.)
if (assignedGrades.get(s) != null) return false;
// First, we create a new TranscriptEntry object. Note
// that we are passing in a reference to THIS Section,
// because we want the TranscriptEntry object,
// as an association class ..., to maintain
// "handles" on the Section as well as on the Student.
// (We'll let the TranscriptEntry constructor take care of
// "hooking" this T.E. to the correct Transcript.)
TranscriptEntry te = new TranscriptEntry(s, grade, this);
// Then, we "remember" this grade because we wish for
// the connection between a T.E. and a Section to be
// bidirectional.
assignedGrades.put(s, te);
return true;
}
public boolean isSectionOf(Course c) {
if (c == representedCourse) return true;
else return false;
}
}