srs.java

java beginning课本上代码的实现

// SRS.java - Chapter 14, Java 5 version.

// Copyright 2005 by Jacquie Barker - all rights reserved.

// The main driver for the command-line driven version of the SRS.


import java.util.ArrayList;

public class SRS {
	// We can effectively create "global" data by declaring
	// collections of objects as public static attributes in 
	// the main class; these can then be accessed throughout the
	// SRS application as:  SRS.collectionName; e.g., SRS.faculty.  

	public static ArrayList<Professor> faculty; 
	public static ArrayList<Student> studentBody; 
	public static ArrayList<Course> courseCatalog; 

	// The next collection -- of Section object references -- is encapsulated 
	// within a special-purpose class by virtue of how we modeled the SRS in UML; 
	// note that we could have encapsulated the preceding three collections in 
	// similar fashion, and will in fact do so in Chapter 15.

	public static ScheduleOfClasses scheduleOfClasses = 
		      new ScheduleOfClasses("SP2005");
	
	public static void main(String[] args) {
		Professor p1, p2, p3;
		Student s1, s2, s3;
		Course c1, c2, c3, c4, c5;
		Section sec1, sec2, sec3, sec4, sec5, sec6, sec7;

		// Create various objects by calling the appropriate 
		// constructors.  (We'd normally be reading in such data
		// from a database or file ...)

		// -----------
		// Professors.
		// -----------

		p1 = new Professor("Jacquie Barker", "123-45-6789", 
				   "Adjunct Professor", "Information Technology");		

		p2 = new Professor("John Smith", "567-81-2345",
				   "Full Professor", "Chemistry");		

		p3 = new Professor("Snidely Whiplash", "987-65-4321",
				   "Full Professor", "Physical Education");		

		// Add these to the appropriate ArrayList.

		faculty = new ArrayList<Professor>();
		faculty.add(p1);
		faculty.add(p2);
		faculty.add(p3);

		// ---------
		// Students.
		// ---------
		
		s1 = new Student("Joe Blow", "111-11-1111", "Math", "M.S.");

		s2 = new Student("Fred Schnurd", "222-22-2222", 
				 "Information Technology", "Ph. D.");

		s3 = new Student("Mary Smith", "333-33-3333", "Physics", "B.S.");

		// Add these to the appropriate ArrayList.

		studentBody = new ArrayList<Student>();
		studentBody.add(s1);
		studentBody.add(s2);
		studentBody.add(s3);

		// --------
		// Courses.
		// --------
		
		c1 = new Course("CMP101",
				"Beginning Computer Technology", 3.0);

		c2 = new Course("OBJ101", 
				"Object Methods for Software Development", 3.0);

		c3 = new Course("CMP283", 
				"Higher Level Languages (Java)", 3.0);

		c4 = new Course("CMP999",
				"Living Brain Computers", 3.0);

		c5 = new Course("ART101",
				"Beginning Basketweaving", 3.0);

		// Add these to the appropriate ArrayList.

		courseCatalog = new ArrayList<Course>();
		courseCatalog.add(c1);
		courseCatalog.add(c2);
		courseCatalog.add(c3);
		courseCatalog.add(c4);
		courseCatalog.add(c5);

		// Establish some prerequisites (c1 => c2 => c3 => c4).

		c2.addPrerequisite(c1);
		c3.addPrerequisite(c2);
		c4.addPrerequisite(c3); 

		// ---------
		// Sections.
		// ---------

		// Schedule sections of each Course by calling the
		// scheduleSection method of Course (which internally
		// invokes the Section constructor). 

		sec1 = c1.scheduleSection('M', "8:10 - 10:00 PM", "GOVT101", 30);

		sec2 = c1.scheduleSection('W', "6:10 - 8:00 PM", "GOVT202", 30);

		sec3 = c2.scheduleSection('R', "4:10 - 6:00 PM", "GOVT105", 25);

		sec4 = c2.scheduleSection('T', "6:10 - 8:00 PM", "SCI330", 25);

		sec5 = c3.scheduleSection('M', "6:10 - 8:00 PM", "GOVT101", 20);

		sec6 = c4.scheduleSection('R', "4:10 - 6:00 PM", "SCI241", 15);
		
		sec7 = c5.scheduleSection('M', "4:10 - 6:00 PM", "ARTS25", 40);
		
		// Add these to the Schedule of Classes.

		scheduleOfClasses.addSection(sec1);
		scheduleOfClasses.addSection(sec2);
		scheduleOfClasses.addSection(sec3);
		scheduleOfClasses.addSection(sec4);
		scheduleOfClasses.addSection(sec5);
		scheduleOfClasses.addSection(sec6);
		scheduleOfClasses.addSection(sec7);

		// Recruit a professor to teach each of the sections.

		p3.agreeToTeach(sec1);
		p2.agreeToTeach(sec2);
		p1.agreeToTeach(sec3);
		p3.agreeToTeach(sec4);
		p1.agreeToTeach(sec5);
		p2.agreeToTeach(sec6);
		p3.agreeToTeach(sec7);

		System.out.println("===============================");
		System.out.println("Student registration has begun!");
		System.out.println("===============================");
		System.out.println();

		// Simulate students attempting to enroll in sections of
		// various courses.

		System.out.println("Student " + s1.getName() + 
				   " is attempting to enroll in " +
				   sec1.toString());

		EnrollmentStatus status = sec1.enroll(s1);
		reportStatus(status);

		// Note the use of a special "housekeeping" method above, reportStatus(), 
		// to interpret and display the outcome of this enrollment request.
		// We could have combined the preceding two lines with
		// a single line instead, as follows:
		//
		//	reportStatus(sec1.enroll(s1));
		//
		// And, since the println() call just above that is also going to
		// be repeated multiple times, we could have combined ALL THREE 
		// LINES of code into a SINGLE line as follows:
		//
		//      attemptToEnroll(s1, sec1);
		// 
		// by writing a more elaborate "housekeeping" method, attemptToEnroll().
	 	// We will, in fact, do so, and will use the more concise syntax for the 
		// remainder of this program.

		// Try concurrently enrolling the same Student in a different Section
		// of the SAME Course!  This should fail.

		attemptToEnroll(s1, sec2);

		// This enrollment request should be fine ...

		attemptToEnroll(s2, sec2);

		// ... but here, the student in question hasn't satisfied the
		// prerequisities, so the enrollment request should be rejected.

		attemptToEnroll(s2, sec3);

		// These requests should both be fine. 

		attemptToEnroll(s2, sec7);
		attemptToEnroll(s3, sec1);

		// When the dust settles, here's what folks wound up
		// being SUCCESSFULLY registered for:
		//
		// sec1:  s1, s3
		// sec2:  s2
		// sec7:  s2

		// Semester is finished (boy, that was quick!).  
		// Professors assign grades for specific students.

		sec1.postGrade(s1, "C+");
		sec1.postGrade(s3, "A");
		sec2.postGrade(s2, "B+");
		sec7.postGrade(s2, "A-");
	
		// Let's see if everything got set up properly
		// by calling various display() methods.
		
		System.out.println("====================");
		System.out.println("Schedule of Classes:");
		System.out.println("====================");
		System.out.println();
		scheduleOfClasses.display();

		System.out.println("======================");
		System.out.println("Professor Information:");
		System.out.println("======================");
		System.out.println();
		p1.display();
		p2.display();
		p3.display();

		System.out.println("====================");
		System.out.println("Student Information:");
		System.out.println("====================");
		System.out.println();
		s1.display();
		s2.display();
		s3.display();
	}

	// Note that this is a private static housekeeping method ...

	private static void reportStatus(EnrollmentStatus s) {
		System.out.println("Status:  " + s.value());
		System.out.println();
	}

	// ... as is this.

	private static void attemptToEnroll(Student s, Section sec) {
		System.out.println("Student " + s.getName() + 
				   " is attempting to enroll in " +
				   sec.toString());

		// Utilize one housekeeping method from within another!
		reportStatus(sec.enroll(s));
	}
}