Hi guys im trying to get back to coding after a long break and im running into some problems. Im building a program which has a library of user uploaded books(not really uploading anything) and im running into an
Exception in thread "main" java.lang.NullPointerException
at Library.beans.User.uploadBook(User.java:107)
at Library.LibraryApplication.main(LibraryApplication.java:22)
when im trying to add a new book via a user.Im using spring btw.
coding snippets
User bean
@Entity
@Table(name = "Users")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
@Column(nullable = false, unique = true)
private String email;
@Column(nullable = false)
private String password;
@Column(nullable = false, unique = true)
private String userName;
// ** Books added to a user private library **
@ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private List<Book> userLibrary;
// ** Books uploaded by user **
@OneToMany(cascade = CascadeType.ALL)
private List<Book> userBooks;
public User(String email, String password, String name) {
super();
this.email = email;
this.password = password;
this.userName = name;
}
public void uploadBook(Book book) {
this.userBooks.add(book);
}
Book bean
@Entity
@Table(name = "Books")
public class Book {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
@Column(nullable = false)
private String name;
@Column(nullable = false)
private String synopsis;
@Column
private String image;
@Column
private double rating;
@Column
private GenreType genre;
@ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private User author;
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private List<Review> reviews;
The code in main which causes the exception
User user = new User("admin", "admin", "user1");
user.uploadBook(new Book("book1", "a", "b", GenreType.Action));
Extra notes If i creat a book outside a user by (book new book) and add an author to the ctr it works one way,the book will state its author is the "user" i inputed on creation but the same "user" wont have it listed under his uploaded books list. what am i missing here?
