Spring：无法确定类型：java.util.List

Question

I have the following scenario: I have a Student class and students table. I have Course class and courses table. Every student and course have unique ID. I would like to put a List into the Student class which is mapped by courses IDs.

I have tried a lot of annotations and relations but nothing succeeded

@Entity
@Table(name = "courses")
public class Course {

    private long id;
    private String name;

    public Course() {

    }

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

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    @Column(name = "name", nullable = false)
    public String getName() {
        return name;
    }

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

}

@Entity
@Table(name = "students")
public class Student {

    private long id;
    private String name;
    @OneToMany(cascade = CascadeType.ALL)
    private List<Course> courses = new ArrayList<>();

    public Student() {

    }

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    @Column(name = "name", nullable = false)
    public String getName() {
        return name;
    }

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

    public List<Course> getCourses() {
        return courses;
    }

    public void setCourses(List<Course> courses) {
        this.courses = courses;
    }
}

Can you help me hot to achieve that because i am a little newbie into the spring

Answer 1

Use the following when declaring one to many relation

@Column(name="course_id")
private Set<Course> courses;

Answer 2

You need to use OneToMany annotation.

@OneToMany(mappedBy = "students", cascade = CascadeType.ALL)
private List<Course> courses;

Answer 3

You need to give your list a type. For instance List<Courses> courseList = new ArrayList<>();