package com.model;
import java.util.HashSet;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToMany;

@Entity
public class Teacher {
    private int id;
    private String name;
    private HashSet<Student> students = new HashSet<Student>();
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @ManyToMany
    public HashSet<Student> getStudents() {
        return students;
    }
    public void setStudents(HashSet<Student> students) {
        this.students = students;
    }
}

package com.model;

import java.util.HashSet;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.ManyToMany;

@Entity
public class Student {
    private int id;
    private String name;
    private HashSet<Teacher> teahcers = new HashSet<Teacher>();
    
    @ManyToMany(mappedBy="students")
    public HashSet<Teacher> getTeahcers() {
        return teahcers;
    }
    public void setTeahcers(HashSet<Teacher> teahcers) {
        this.teahcers = teahcers;
    }
    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    
}