Hibernate - Nullpointer beim Abrufen der Liste/Set

Question

Das ist mein Users.java

package com.serwis.model; 


import javax.persistence.*; 

import java.util.Arrays; 
import java.util.Set; 


@Entity 
@Table(name="Users") 
public class Users { 

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

    @Column(name="login") 
    private String login; 

    @Column(name="password") 
    private String password; 

    @Column(name="email") 
    private String email; 

    @Column(name="avatar") 
    private byte[] avatar; 

    @OneToMany(mappedBy="users", cascade = CascadeType.ALL,fetch = FetchType.EAGER) 
    private Set<Post> posts; 

    public Users(){} 

    public Users(int id, String login, String password, String email, byte[] avatar) { 
     this.id = id; 
     this.login = login; 
     this.password = password; 
     this.email = email; 
     this.avatar = avatar; 
    } 


    public Users(byte[] avatar, String email, String password, String login) { 
     this.avatar = avatar; 
     this.email = email; 
     this.password = password; 
     this.login = login; 
    } 

    @Override 
    public String toString() { 
     return "Users{" + 
       "id=" + id + 
       ", login='" + login + '\'' + 
       ", password='" + password + '\'' + 
       ", email='" + email + '\'' + 
       ", avatar=" + 
       ", posts=" + posts.size()+ 
       '}'; 
    } 

    public int getId() { 
     return id; 
    } 

    public void setId(int id) { 
     this.id = id; 
    } 

    public String getLogin() { 
     return login; 
    } 

    public void setLogin(String login) { 
     this.login = login; 
    } 

    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 byte[] getAvatar() { 
     return avatar; 
    } 

    public void setAvatar(byte[] avatar) { 
     this.avatar = avatar; 
    } 


} 

Post.java

import javax.persistence.*; 
import java.util.Date; 


@Entity 
@Table(name="Post") 
public class Post { 

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


    @Column(name="content") 
    private String content; 

    @Column(name="date") 
    private Date date; 

    @Column(name="tags") 
    private String tags; 

    @ManyToOne 
    @JoinColumn(name="id") 
    private Users users; 

    public Post(){} 

    public Post(String content, Date date, String tags) { 
     this.content = content; 
     this.date = date; 
     this.tags = tags; 
    } 

    public Post(String content, Date date, String tags, Users users) { 
     this.content = content; 
     this.date = date; 
     this.tags = tags; 
     this.users = users; 
    } 

    @Override 
    public String toString() { 
     return "Post{" + 
       "id=" + id + 
       ", content='" + content + '\'' + 
       ", date=" + date + 
       ", tags='" + tags + '\'' + 
       ", users=" + users + 
       '}'; 
    } 

    public int getId() { 
     return id; 
    } 

    public void setId(int id) { 
     this.id = id; 
    } 

    public Users getUsers() { return users; } 

    public void setUsers(Users users) { this.users = users; } 

    public String getContent() { 
     return content; 
    } 

    public void setContent(String content) { 
     this.content = content; 
    } 

    public Date getDate() { 
     return date; 
    } 

    public void setDate(Date date) { 
     this.date = date; 
    } 

    public String getTags() { 
     return tags; 
    } 

    public void setTags(String tags) { 
     this.tags = tags; 
    } 
} 

Test.java Paket com.serwis;

import com.serwis.model.Chat; 
import com.serwis.model.Photo; 
import com.serwis.model.Post; 
import com.serwis.model.Users; 
import org.hibernate.Query; 
import org.hibernate.Session; 
import org.hibernate.SessionFactory; 
import org.hibernate.boot.registry.StandardServiceRegistryBuilder; 
import org.hibernate.cfg.Configuration; 
import org.hibernate.service.ServiceRegistry; 

import java.util.List; 


/** 
* Created by Jodanpotasu on 2016-07-17. 
*/ 
public class TEST { 

    public static void main(String[] args){ 
     Configuration configuration = new Configuration().configure().addAnnotatedClass(Users.class).addAnnotatedClass(Post.class); 
     ServiceRegistry serviceRegistry 
       = new StandardServiceRegistryBuilder() 
       .applySettings(configuration.getProperties()).build(); 

     // builds a session factory from the service registry 
     SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry); 



     try{ 
      Users user = new Users(null,"YYYYYYYYYYYYY","dupa","dupa"); 
      Post post = new Post("content",null,"tags",user); 

      Session session = sessionFactory.openSession(); 
      session.beginTransaction(); 
      session.save(user); 
      session.save(post); 

      Query query = session.createQuery("from Users"); 
      List list = query.list(); 

      Query query1 = session.createQuery("from Post"); 
      List list1 = query1.list(); 

      session.getTransaction().commit(); 


      session.close(); 

      System.out.println(list); 

      System.out.println("post"); 
      System.out.println(list1); 

     }catch (Exception e){ 
      System.out.println("blad\n\n"); 
      System.out.println(e); 
     } finally { 
      System.out.println("zrobiono"); 
     } 





    } 
} 

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?> 
<!DOCTYPE hibernate-configuration PUBLIC 
     "-//Hibernate/Hibernate Configuration DTD//EN" 
     "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> 

<hibernate-configuration> 
    <session-factory> 
     <!-- JDBC connection settings --> 
     <property name="hibernate.connection.driver_class">org.hsqldb.jdbcDriver</property> 
     <property name="connection.url">jdbc:hsqldb:file:database/serwisDB;hsqldb.write_delay=false;shutdown=true;</property> <!--shutdown=true; --> 
     <property name="connection.username">sa</property> 
     <property name="connection.password"></property> 
     <!--https://www.progress.com/jdbc/resources/tutorials/connection-pooling/connection --> 
     <property name="connection.pool_size">1</property> 

     <!-- SQL DIALECT --> 
     <property name="hibernate.dialect">org.hibernate.dialect.HSQLDialect</property> 

     <!-- SHOW SQL OUTPUT --> 
     <property name="show_sql">true</property> 

     <property name="hibernate.current_session_context_class">thread</property> 

     <property name="hibernate.hbm2ddl.auto">update</property> 



    </session-factory> 
</hibernate-configuration> 

Ausgabe von Konsolen

java.lang.NullPointerException 
zrobiono 
22:40:25.391 [pool-1-thread-1] DEBUG org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl - Connection pool now considered primed; min-size will be maintained 

Process finished with exit code -1 

Mein Problem ist, dass ich verstehe nicht, warum es nicht funktioniert, wo ich einige Fehler haben. Ich habe versucht, Change Set auf List, später FetchType.EAGER etc. aber nichts funktioniert.

Struktur: < 1, viele> - Benutzer, Post

i für neueste Hibernate jede gutes Tutorial nicht sehen :(

Answer 1

Ihre Users Klasse einige öffentliche Zugriff auf die Sammlung von Post muss, und Sie müssen sowohl das Post-Objekt in die Sammlung, und legen Sie es User-Objekt. es sollte in etwa so aussehen.

 Users user = new Users(null,"YYYYYYYYYYYYY","dupa","dupa"); 
     Post post = new Post("content",null,"tags",user); 
     user.getPosts().add(post); 

Answer 2

die folgende Methode in Ihnen Benutzerklasse Werfen Sie den Fehler:

@Override public String toString() { return "Users{" + "id=" + id + ", login='" + login + '\'' + ", password='" + password + '\'' + ", email='" + email + '\'' + ", avatar=" + ", posts=" + posts.size()+ '}'; }

Bitte ein Null-Check für posts.size() hinzufügen.

Zusätzlich, wenn Sie nicht verstehen können, warum Sie einen Fehler erhalten, drucken Sie bitte den Stack-Trace/Debug den Fehler.