Hibernate @OneToMany

@Entity
public class Player
{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    private String nick;

    @ManyToOne
    private Team team;
}

@Entity
public class Team
{
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    private String name;

    @OneToMany(mappedBy = "team")
    private List<Player> players = new ArrayList<>();

    @Transient
    public void addPlayer(Player player)
    {
        if (player != null)
            players.add(player);
    }
}

private void addTeams()
    {
        Team team = new Team();
        team.setName("Name"); 

        Player p = new Player();
        team.addPlayer(p); // wstawia nulla do team_id w bazie danych
        // p.addTeam(team); // wstawia dobry klucz do team_id
        teamsService.addTeam(team);  
        playersService.addPlayer(p); 
    } 

@OneToMany( mappedBy = "team", cascade=CascadeType.ALL )
	private List<Player> players;

Player p = new Player();
team.addPlayer(p); // wstawia nulla do team_id w bazie danych
// p.addTeam(team); // wstawia dobry klucz do team_id
teamsService.addTeam(team);  
playersService.addPlayer(p); 

teamsService.addTeam(team);  //zapisze team z playerem
playersService.addPlayer(p);  //nadpisze playera jeszcze raz pustym teamem (bo nie ustawiles?)

 
private void addTeams()
    {
        Team team = new Team();
        team.setName("Name"); 
 
        Player p = new Player();
        p.addTeam(team)
         Session session = sessionFactory.getSession();
         session.beginTransaction();
         session.saveOrUpdate(p);
         session.currentTransaction().commit();
         session.close();
        
    }

private void addTeams()
	{
		++t;
		Team team = new Team();
		team.setName("Name " + Integer.toString(t));
		Player p = new Player();
		p.setAge(10 + t);
		p.setDescription("Opis gracza nr " + Integer.toString(t));
		p.setNick("Nick " + Integer.toString(t));

		team.getPlayers().add(p);
		
		teamsService.addTeam(team);
		//playersService.addPlayer(p);

	}

package eniupage.domain.repository.impl;

import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.util.List;

import javax.inject.Inject;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.transaction.annotation.Transactional;

import eniupage.domain.repository.Dao;

public abstract class DaoImpl<T> implements Dao<T>
{
	@Inject
	private SessionFactory sessionFactory;

	private Class<T> domainClass;

	protected Session currentSession()
	{
		return sessionFactory.getCurrentSession();

	}

	@SuppressWarnings("unchecked")
	private Class<T> getDomainClass()
	{
		if (domainClass == null)
		{
			ParameterizedType thisType = (ParameterizedType) getClass().getGenericSuperclass();
			this.domainClass = (Class<T>) thisType.getActualTypeArguments()[0];
		}
		return domainClass;
	}

	private String getDomainClassName()
	{
		return getDomainClass().getName();
	}

	@Transactional
	public void add(T t)
	{
		currentSession().save(t);
	}

	@Transactional
	@SuppressWarnings("unchecked")
	public List<T> getAll()
	{
		return currentSession().createQuery("from " + getDomainClassName()).list();
	}

	@Transactional
	@SuppressWarnings("unchecked")
	public T get(Serializable id)
	{
		return (T) currentSession().get(getDomainClass(), id);
	}

	@Transactional
	public void update(T t)
	{
		currentSession().update(t);
	}

	@Transactional
	@SuppressWarnings("unchecked")
	public T load(Serializable id)
	{
		return (T) currentSession().load(getDomainClass(), id);
	}

	@Transactional
	public long count()
	{
		return (Long) currentSession().createQuery("select count(*) from " + getDomainClassName()).uniqueResult();
	}
}

package eniupage.cfg;

import java.util.Properties;

import javax.sql.DataSource;

import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate4.HibernateTransactionManager;
import org.springframework.orm.hibernate4.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Configuration
@ComponentScan(basePackages = { "eniupage" }, excludeFilters = {
		@Filter(type = FilterType.ANNOTATION, value = EnableWebMvc.class) })
@EnableTransactionManagement
public class RootConfig
{
	@Bean
	public DataSource dataSource()
	{
		DriverManagerDataSource dataSource = new DriverManagerDataSource();
		dataSource.setDriverClassName( "com.mysql.jdbc.Driver" );
		dataSource.setUrl( "jdbc:mysql://localhost:3306/eniupage" );
		dataSource.setUsername( "eniupage" );
		dataSource.setPassword( "password" );
		return dataSource;
	}
	
	@Autowired
	@Bean
	public LocalSessionFactoryBean sessionFactory( DataSource dataSource )
	{
		LocalSessionFactoryBean sfb = new LocalSessionFactoryBean();
		sfb.setDataSource( dataSource );
		sfb.setPackagesToScan( new String[] { "eniupage.domain"} );
		Properties props = new Properties();
		props.setProperty( "hibernate.dialect", "org.hibernate.dialect.MySQLDialect" );
		props.setProperty( "hibernate.hbm2ddl.auto", "create-drop" );
		
		sfb.setHibernateProperties( props );
		return sfb;
	}
	
	
	
	@Bean
	public BeanPostProcessor persistenceTranslation()
	{
		return new PersistenceExceptionTranslationPostProcessor();
	}
	
	@Autowired
	@Bean(name = "transactionManager")
	public HibernateTransactionManager getTransactionManager(
	        SessionFactory sessionFactory) {
	    HibernateTransactionManager transactionManager = new HibernateTransactionManager(
	            sessionFactory);
	 
	    return transactionManager;
	}
}

 
 team.getPlayers().add(p);
 teamsService.addTeam(team);

 
private void addTeams()
    {
        ++t;
        Team team = new Team();
        team.setName("Name " + Integer.toString(t));
        Player p = new Player();
        p.setAge(10 + t);
        p.setDescription("Opis gracza nr " + Integer.toString(t));
        p.setNick("Nick " + Integer.toString(t));
 
        team.getPlayers().add(p);
        teamsService.addTeam(team);
    }

@Entity
@Table(name="DEPARTMENT")
public class Department {
 
    @Id
    @GeneratedValue
    @Column(name="DEPARTMENT_ID")
    private Long departmentId;
     
    @Column(name="DEPT_NAME")
    private String departmentName;
     
    @OneToMany(mappedBy="department")
    private Set<Employee> employees;
 
    // Getter and Setter methods
}

@Entity
@Table(name="EMPLOYEE")
public class Employee {
 
    @Id
    @GeneratedValue
    @Column(name="employee_id")
    private Long employeeId;
     
    @Column(name="firstname")
    private String firstname;
     
    @Column(name="lastname")
    private String lastname;
     
    @Column(name="birth_date")
    private Date birthDate;
     
    @Column(name="cell_phone")
    private String cellphone;
 
    @ManyToOne
    @JoinColumn(name="department_id")
    private Department department;
     
    public Employee() {
         
    }
     
    public Employee(String firstname, String lastname, String phone) {
        this.firstname = firstname;
        this.lastname = lastname;
        this.birthDate = new Date(System.currentTimeMillis());
        this.cellphone = phone;
    }
 
    // Getter and Setter methods
}

public class Main {
 
    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
 
        SessionFactory sf = HibernateUtil.getSessionFactory();
        Session session = sf.openSession();
        session.beginTransaction();
 
        Department department = new Department();
        department.setDepartmentName("Sales");
        session.save(department);
         
        Employee emp1 = new Employee("Nina", "Mayers", "111");
        Employee emp2 = new Employee("Tony", "Almeida", "222");
 
        emp1.setDepartment(department);
        emp2.setDepartment(department);
         
        session.save(emp1);
        session.save(emp2);
 
        session.getTransaction().commit();
        session.close();
    }
}

public void addPlayer(Player player)
{
    players.add(player);
    player.setTeam(this);
}

Team t1 = new Team();
Team t2 = new Team();
Player player = new Player();
t1.add(player);
t2.add(player);