Course
import java.util.ArrayList;
import java.util.List;

public class Course {
	private String name;
	private float grade;
	private List<Student> allStudents;
	
	public Course(String name,float grade){
		this.setAllStudents(new ArrayList<Student>());
		this.setGrade(grade);
		this.setName(name);
	}
	public void addStu(Student student){
		this.allStudents.add(student);
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public float getGrade() {
		return grade;
	}
	public void setGrade(float grade) {
		this.grade = grade;
	}
	public List<Student> getAllStudents() {
		return allStudents;
	}
	public void setAllStudents(List<Student> allStudents) {
		this.allStudents = allStudents;
	}
}

Student
import java.util.ArrayList;
import java.util.List;

public class Student {
	private String name;
	private int age;
	private List<Course> allCourse;//一個學(xué)生可以選多門課
	
	public Student(String name,int age){
		this.setAge(age);
		this.setAllCourse(new ArrayList<Course>());
		this.setName(name);
	}
	public void addCourse(Course course){
		this.allCourse.add(course);
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public List<Course> getAllCourse() {
		return allCourse;
	}
	public void setAllCourse(List<Course> allCourse) {
		this.allCourse = allCourse;
	}
}

TestCourse
import java.util.Iterator;

public class TestCourse {
	public static void main(String[] args) {
		Student stu1 = new Student("張三",20);
		Student stu2 = new Student("李四",21);
		Student stu3 = new Student("王五",22);
		Student stu4 = new Student("趙柳",23);
		Student stu5 = new Student("孫琦",24);
		Course c1 = new Course("Java se 基礎(chǔ)",2.0f);
		Course c2 = new Course("Java se web",3.0f);
		Course c3 = new Course("分布式開發(fā)",5.0f);
//		設(shè)置關(guān)系
		stu1.addCourse(c1);
		c1.addStu(stu1);
		stu1.addCourse(c2);
		c2.addStu(stu1);
		
		stu2.addCourse(c2);
		c2.addStu(stu2);
		
		stu3.addCourse(c1);
		c1.addStu(stu3);
		stu3.addCourse(c2);
		c2.addStu(stu3);
		stu3.addCourse(c3);
		c3.addStu(stu3);
		
		stu4.addCourse(c3);
		c3.addStu(stu4);
		
		stu5.addCourse(c3);
		c3.addStu(stu5);
		
		System.out.println("學(xué)生姓名："+stu1.getName());
		Iterator<Course> it1 = stu1.getAllCourse().iterator();
		while(it1.hasNext()){
			Course c = it1.next();
			System.out.println("\t|-課程名稱："+c.getName()+",學(xué)分："+c.getGrade());
		}
		
		System.out.println("課程名稱："+c3.getName());
		Iterator<Student> it2 = c3.getAllStudents().iterator();
		while(it2.hasNext()){
			Student s = it2.next();
			System.out.println("\t|-學(xué)生姓名："+s.getName()+",年齡："+s.getAge());
		}
	}

}