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java - 异常描述：NullPointerException

问题描述

我正在使用 postgresql 数据库在 java 中开发一个项目，当我尝试插入数据时，或者更确切地说，当我提交时，我遇到了问题。看起来它来自 ID (game_id) 的问题，但我不知道是什么。

这是我的实体的代码：

@Entity
@Cacheable(true)
@Table(name = "game")
@Multitenant(MultitenantType.TABLE_PER_TENANT)
@TenantTableDiscriminator(type = TenantTableDiscriminatorType.SCHEMA, contextProperty = PersistenceUnitProperties.MULTITENANT_PROPERTY_DEFAULT)


public class Game implements Serializable{
    private static final long serialVersionUID = 1L;

    @Id
    @Column(name = "game_id", unique = true, nullable = false)
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer gameId;

    @Column(name = "game_title", length = 256)
    private String gameTitle;

    @Temporal(TemporalType.DATE)
    @Column(name = "game_released")
    private Date gameReleased;

    @Column(name = "game_img")
    private Byte[] gameImg;

    @Column(name = "game_desc", length = 3072)
    private String gameDesc;

这是我尝试插入数据的方式：

EntityManagerFactory emf = Persistence.createEntityManagerFactory("projet_nintendo");
        EntityManager em = emf.createEntityManager();   
        EntityTransaction transac = em.getTransaction();
        transac.begin();



        for(int ii = 0; ii < array.length(); ii++) {
            Game g = new Game();
            g.setGameId(Conversion.stringEnInt(array.getJSONObject(ii).getString("fs_id")));
            g.setGameTitle(array.getJSONObject(ii).getString("title"));

            JSONArray test = array.getJSONObject(ii).getJSONArray("dates_released_dts");
            try {
                SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
                Date parsedDate = dateFormat.parse(test.getString(0));
                g.setGameReleased(parsedDate);
            } catch(Exception e) { 
            }
            em.persist(g);


            System.err.println(array.getJSONObject(ii).getString("pretty_date_s"));
        }

        transac.commit();
        em.close();
        emf.close();

我有这个错误：

Exception in thread "main" javax.persistence.RollbackException: Exception [EclipseLink-69] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DescriptorException
Exception Description: A NullPointerException was thrown while extracting a value from the instance variable [gameId] in the object [database.orm.Game].
Internal Exception: java.lang.NullPointerException
Mapping: org.eclipse.persistence.mappings.DirectToFieldMapping[gameId-->game.game_id]
Descriptor: RelationalDescriptor(database.orm.Game --> [DatabaseTable(game)])
    at org.eclipse.persistence.internal.jpa.transaction.EntityTransactionImpl.commit(EntityTransactionImpl.java:157)
    at test.main(test.java:79)
Caused by: Exception [EclipseLink-69] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd)

你能告诉我我做错了什么吗？

标签： javapostgresqljpaeclipselink

解决方案

try(EntityManager em = emf.createEntityManager();   
    EntityTransaction transac = em.getTransaction()){

    ...
}
// don't need to close here em.. emf..

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