Map collections of primitives

Sometimes, you need to associate your entity with a collection of primitive values to represent a simple one/many-to-many relationship. For example, each movie has a set of associated genres that we want to keep stored in the database. To represent them from an object-oriented perspective, we will define a list (collection) of strings in our Movie class. To reflect this relationship inside the database, we will use the @ElementCollecion annotation, as shown in the following example:

@Entity 
public class Movie { 
 
    @Id 
    @GeneratedValue 
    private long id; 
    private String title; 
    @ElementCollection 
    private List<String> genres = new ArrayList<>(); 
 
    public Movie() { 
    } 
    // getters and setters here 
} 

The @ElementCollection annotation will make the JPA provider create another table (movie_genres) to store the list of genres, mapped to the movies table using the movie's primary key as a secondary key in the (movie_genres...