java beginning课本上代码的实现

				// Course.java - Chapter 14, Java 5 version.
				
				// Copyright 2005 by Jacquie Barker - all rights reserved.
				
				// A MODEL class.
				
				
				import java.util.ArrayList;
				import java.util.Collection;
				
				public class Course {
					//------------
					// Attributes.
					//------------
				
					private String courseNo;
					private String courseName;
					private double credits;
					private ArrayList offeredAsSection; 
					private ArrayList prerequisites; 
					
					//----------------
					// Constructor(s).
					//----------------
				
					public Course(String cNo, String cName, double credits) {
						setCourseNo(cNo);
						setCourseName(cName);
						setCredits(credits);
				
						// Note that we're instantiating empty support Collection(s).
				
						offeredAsSection = new ArrayList();
						prerequisites = new ArrayList();
					}
				
					//------------------
					// Accessor methods.
					//------------------
				
					public void setCourseNo(String cNo) {
						courseNo = cNo;
					}
					
					public String getCourseNo() {
						return courseNo;
					}
					
					public void setCourseName(String cName) {
						courseName = cName;
					}
					
					public String getCourseName() {
						return courseName;
					}
					
					public void setCredits(double c) {
						credits = c;
					}
					
					public double getCredits() {
						return credits;
					}
					
					//-----------------------------
					// Miscellaneous other methods.
					//-----------------------------
				
					public void display() {
						System.out.println("Course Information:");
						System.out.println("\tCourse No.:  " + getCourseNo());
						System.out.println("\tCourse Name:  " + getCourseName());
						System.out.println("\tCredits:  " + getCredits());
						System.out.println("\tPrerequisite Courses:");
				
						for (Course c : prerequisites) {
							System.out.println("\t\t" + c.toString());
						}
				
						// Note use of print vs. println in next line of code.
				
						System.out.print("\tOffered As Section(s):  ");
						for (Section s : offeredAsSection) {
							System.out.print(s.getSectionNo() + " ");
						}
				
						// Finish with a blank line.
				
						System.out.println();
					}
					
					public String toString() {
						return getCourseNo() + ":  " + getCourseName();
					}
				
					public void addPrerequisite(Course c) {
						prerequisites.add(c);
					}
				
					public boolean hasPrerequisites() {
						if (prerequisites.size() > 0) return true;
						else return false;
					}
				
					public Collection getPrerequisites() {
						return prerequisites;
					}
				
					public Section scheduleSection(char day, String time, String room,
								       int capacity) {
						// Create a new Section (note the creative way in
						// which we are assigning a section number) ...
				
						Section s = new Section(offeredAsSection.size() + 1, 
								day, time, this, room, capacity);
						
						// ... and then remember it!
				
						addSection(s);
						
						return s;
					}
				
					public void addSection(Section s) {
						offeredAsSection.add(s);
					}
				}