java:类集操作,多对多的关系

java:类集操作,多对多的关系

//一个课程有多个学生报名，
//一个学生可以报名多个课程

demo.java, Student.java, Course.java'

public class Course {

private String name;
private int course;
private List<Student> allStudent;

public Course() {
this.allStudent = new ArrayList<Student>();
}

public Course(String name, int course) {
this();
this.name = name;
this.course = course;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getCourse() {
return course;
}

public void setCourse(int course) {
this.course = course;
}

public List<Student> getAllStudent() {
return allStudent;
}

public String toString()
{
return "课程："+this.name +",学分："+this.course;
}

}

　　

Student.java

public class Student {

private String name;
private int age;
private List<Course> allCourse;

public Student() {
this.allCourse = new ArrayList<Course>();
}

public Student(String name, int age) {
this();
this.name = name;
this.age = age;

}

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 String toString()
{
return "学生："+this.name + ",年龄："+this.age;
}

}

　　

demo.java

//一个学生可以报名多个课程
Course c1 = new Course("java",5);
Course c2 = new Course("linux",5);

Student st1 = new Student("张三",22);
Student st2 = new Student("李四",33);
Student st3 = new Student("王五",32);
Student st4 = new Student("田七",29);
Student st5 = new Student("赵六",28);

//第一课程
c1.getAllStudent().add(st1);
c1.getAllStudent().add(st3);
st1.getAllCourse().add(c1);
st2.getAllCourse().add(c2);

//第二课程
c2.getAllStudent().add(st1);
c2.getAllStudent().add(st2);
c2.getAllStudent().add(st3);
c2.getAllStudent().add(st4);
c2.getAllStudent().add(st5);
st1.getAllCourse().add(c2);
st2.getAllCourse().add(c2);
st3.getAllCourse().add(c2);
st4.getAllCourse().add(c2);
st5.getAllCourse().add(c2);

//输出
System.out.println(c1);
Iterator<Student> stu = c1.getAllStudent().iterator();
while(stu.hasNext())
{
System.out.println("__" + stu.next());
}
System.out.println(st1);
Iterator<Course> cour = st1.getAllCourse().iterator();
while(cour.hasNext())
{
System.out.println( "__" + cour.next());
}

　　

输出的结果为：

课程：java,学分：5
__学生：张三,年龄：22
__学生：王五,年龄：32
学生：张三,年龄：22
__课程：java,学分：5
__课程：linux,学分：5