public class PersistenceManager {

    private static final SessionFactory factory = new Configuration().configure().buildSessionFactory();
    public static void sampleData() {


        try(Session session = factory.openSession()){

            SampleDataLoader.loadSampleData(session);

        }
        catch(HibernateException e) {
            System.out.println("Exception during persisting! Message: " + e.getMessage());
            e.printStackTrace();
        }

    }
}

public class SampleDataLoader {

    static void loadSampleData(Session session) {

        Language french = new Language("French");
        Language german = new Language("German");

        Noun garcon = new Noun(french, "garcon", false);
        Noun junge = new Noun(german, "Junge", false);

        junge.addTranslation(garcon);

        ZUser user = new ZUser("Daniel", "password");
        user.setOwnLanguage(german);
        user.setEmail("abc@somemail.de");
        user.setDateRegistered(LocalDateTime.now());

        user.addForeignLanguage(french);

        Transaction transaction = session.beginTransaction();
        session.save(user);
        session.save(french);
        session.save(german);
        session.save(junge);
        transaction.commit();
    }
}

@Entity
public class ZUser {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name = "id")
    private int id;

    @Column
    private String name;

    @Column
    private String password;

    @Column
    private String email;

    @Column
    private String picturePath;

    @Column
    private LocalDateTime dateRegistered;

    @ManyToOne(fetch=FetchType.EAGER)
    @JoinColumn(name="OWNLANGUAGE_ID")
    private Language ownLanguage;

    @ManyToMany(cascade = { CascadeType.ALL })
    @JoinTable(name="USER_LANGUAGE",
     joinColumns=@JoinColumn(name="USER_ID"),
     inverseJoinColumns=@JoinColumn(name="LANGUAGE_ID")
    )
    private Set<Language> foreignLanguages = new HashSet<>();

    public ZUser() {}
    public ZUser(String n, String p) {
        name = n;
        password = p;
    }


    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; }
    public String getPassword() { return password; }
    public void setPassword(String password) { this.password = password; }
    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }
    public String getPicturePath() { return picturePath; }
    public void setPicturePath(String picturePath) { this.picturePath = picturePath; }
    public LocalDateTime getDateRegistered() { return dateRegistered; }
    public void setDateRegistered(LocalDateTime dateRegistered) { this.dateRegistered = dateRegistered; }
    public Language getOwnLanguage() { return ownLanguage; }
    public void setOwnLanguage(Language ownLanguage) { this.ownLanguage = ownLanguage; }

    public void addForeignLanguage(Language language) {foreignLanguages.add(language);}
    public Set<Language> getForeignLanguages() {return Collections.unmodifiableSet(foreignLanguages); }
}