Android create方法上的ORMLite异常集

数据库和表的创建已成功通过。 DatabaseHandler类的My onCreate（）：

public void onCreate(SQLiteDatabase db, ConnectionSource connectionSource) 
    {
         try
         {  

            TableUtils.createTable(connectionSource, Category.class);
            TableUtils.createTable(connectionSource, Level.class);
            DataParsing a = new DataParsing();
            a.fillCategories();
            Log.i(DatabaseHandler.class.getName(), "created new entries in onCreate: " );
         }
         catch (SQLException e){
             Log.e(TAG, "error creating DB " + DATABASE_NAME);
             throw new RuntimeException(e);
         } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

我从web服务获取JSON数据，并用GSON解析它。数据在fillcategories（）方法中成功填充类数据。然后我想在saveContacts（）方法中将所有数据放入ORMLite数据库：

---

为什么会发生这种情况？

将我的活动的上下文传递给OrmLiteSqliteOpenHelper解决了这个问题。我使用这些类在整个应用程序生命周期中维护对数据库的访问：

public class ApplicationMemory extends Application{

   @Override
   public void onCreate() {
       super.onCreate();
       HelperFactory.SetHelper(getApplicationContext());
   }
   @Override
   public void onTerminate() {
       HelperFactory.ReleaseHelper();
       super.onTerminate();
   }
}

及

---

其中DatabaseHandler-class，它是从OrmLiteSqliteOpenHelper扩展而来，在我的问题中进行了描述。

这是DataParsing.java？HelperFactory.GetHelper（）.getCategoryDao（）.create（contact）的第61行；主要问题在这里…你应该接受你自己的答案，伙计。

    FATAL EXCEPTION: main
 java.lang.NullPointerException
    at com.library.DataParsing.saveContacts(DataParsing.java:61)
at com.library.DataParsing.fillCategories(DataParsing.java:45)
    at com.library.DatabaseHandler.onCreate(DatabaseHandler.java:85)
    at com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper.onCreate(OrmLiteSqliteOpenHelper.java:169)
    at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:126)
    at com.j256.ormlite.android.AndroidConnectionSource.getReadWriteConnection(AndroidConnectionSource.java:63)
    at com.j256.ormlite.android.AndroidConnectionSource.getReadOnlyConnection(AndroidConnectionSource.java:51)
    at com.j256.ormlite.stmt.StatementExecutor.buildIterator(StatementExecutor.java:202)
    at com.j256.ormlite.stmt.StatementExecutor.query(StatementExecutor.java:155)
    at com.j256.ormlite.stmt.StatementExecutor.queryForAll(StatementExecutor.java:113)
    at com.j256.ormlite.dao.BaseDaoImpl.queryForAll(BaseDaoImpl.java:237)
    at com.assignmentexpert.LoginActivity$1.onClick(LoginActivity.java:97)
    at android.view.View.performClick(View.java:2485)
    at android.view.View$PerformClick.run(View.java:9080)
    at android.os.Handler.handleCallback(Handler.java:587)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:123)
    at android.app.ActivityThread.main(ActivityThread.java:3687)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:507)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
    at dalvik.system.NativeStart.main(Native Method)

public class ApplicationMemory extends Application{

   @Override
   public void onCreate() {
       super.onCreate();
       HelperFactory.SetHelper(getApplicationContext());
   }
   @Override
   public void onTerminate() {
       HelperFactory.ReleaseHelper();
       super.onTerminate();
   }
}

 public class HelperFactory {
 private static DatabaseHandler databaseHelper;

   public static DatabaseHandler GetHelper(){
       return databaseHelper;
   }

public static void SetHelper(Context context){
       databaseHelper = OpenHelperManager.getHelper(context,DatabaseHandler.class);
   }

public static void ReleaseHelper(){
       OpenHelperManager.releaseHelper();
       databaseHelper = null;
   }
   }