Android-помощник SQL-объекта не может прочитать мою базу данных

Question

У меня возникли проблемы с чтением базы данных папок моих ресурсов с помощью SQLite Asset Helper. Я создал новый тестовый проект с новой базой данных, но он не работал снова. вот мой код:

MainActivity:

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     MyDatabase a = new MyDatabase(this); 
     a.getEmployees(); 
    } 
} 

MyDatabase:

public class MyDatabase extends SQLiteAssetHelper { 

    private static final String DATABASE_NAME = "northwind.db"; 
    private static final int DATABASE_VERSION = 1; 

    public MyDatabase(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 

    public Cursor getEmployees() { 
     SQLiteDatabase db = getReadableDatabase(); 
     return null; 
    } 

} 

Я заявил также WRITE_EXTERNAL_STORAGE разрешение. но приложение падает. Может кто-нибудь мне помочь? Благодарю.

(отредактирован) LogCat:

07-21 11:18:52.090 16244-16244/co.rez.myapplication W/dalvikvm: VFY: unable to find class referenced in signature (Landroid/view/SearchEvent;) 
    07-21 11:18:52.090 16244-16244/co.rez.myapplication I/dalvikvm: Could not find method android.view.Window$Callback.onSearchRequested, referenced from method android.support.v7.view.WindowCallbackWrapper.onSearchRequested 
    07-21 11:18:52.090 16244-16244/co.rez.myapplication W/dalvikvm: VFY: unable to resolve interface method 14532: Landroid/view/Window$Callback;.onSearchRequested (Landroid/view/SearchEvent;)Z 
    07-21 11:18:52.090 16244-16244/co.rez.myapplication I/dalvikvm: Could not find method android.view.Window$Callback.onWindowStartingActionMode, referenced from method android.support.v7.view.WindowCallbackWrapper.onWindowStartingActionMode 
    07-21 11:18:52.090 16244-16244/co.rez.myapplication W/dalvikvm: VFY: unable to resolve interface method 14536: Landroid/view/Window$Callback;.onWindowStartingActionMode (Landroid/view/ActionMode$Callback;I)Landroid/view/ActionMode; 
    07-21 11:18:52.150 16244-16244/co.rez.myapplication I/dalvikvm: Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.widget.TintTypedArray.getChangingConfigurations 
    07-21 11:18:52.150 16244-16244/co.rez.myapplication W/dalvikvm: VFY: unable to resolve virtual method 409: Landroid/content/res/TypedArray;.getChangingConfigurations()I 
    07-21 11:18:52.150 16244-16244/co.rez.myapplication I/dalvikvm: Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.widget.TintTypedArray.getType 
    07-21 11:18:52.150 16244-16244/co.rez.myapplication W/dalvikvm: VFY: unable to resolve virtual method 431: Landroid/content/res/TypedArray;.getType (I)I 
    07-21 11:18:52.240 16244-16244/co.rez.myapplication W/SQLiteAssetHelper: copying database from assets... 
    07-21 11:18:52.240 16244-16244/co.rez.myapplication E/SQLiteAssetHelper: Couldn't open northwind.db for writing (will try read-only): 
    com.readystatesoftware.sqliteasset.SQLiteAssetHelper$SQLiteAssetException: Missing databases/northwind.db file (or .zip, .gz archive) in assets, or target folder not writable 
    at android.content.res.AssetManager.openAsset(Native Method) 
    at android.content.res.AssetManager.open(AssetManager.java:316) 
    at android.content.res.AssetManager.open(AssetManager.java:290) 
    at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.copyDatabaseFromAssets(SQLiteAssetHelper.java:436) 
    at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.createOrOpenDatabase(SQLiteAssetHelper.java:400) 
    at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.getWritableDatabase(SQLiteAssetHelper.java:176) 
    at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.getReadableDatabase(SQLiteAssetHelper.java:254) 
    at co.rez.myapplication.MyDatabase.getEmployees(MyDatabase.java:16) 
    at co.rez.myapplication.MainActivity.onCreate(MainActivity.java:13) 
    at android.app.Activity.performCreate(Activity.java:5326) 
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1090) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2233) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2319) 
    at android.app.ActivityThread.access$1100(ActivityThread.java:135) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1232) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:136) 
    at android.app.ActivityThread.main(ActivityThread.java:5234) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:931) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747) 
    at dalvik.system.NativeStart.main(Native Method) 
    07-21 11:18:52.240 16244-16244/co.rez.myapplication E/SQLiteLog: (14) cannot open file at line 30211 of [00bb9c9ce4] 
    07-21 11:18:52.240 16244-16244/co.rez.myapplication E/SQLiteLog: (14) os_unix.c:30211: (2) open(/data/data/co.rez.myapplication/databases/northwind.db) - 
    07-21 11:18:52.250 16244-16244/co.rez.myapplication E/SQLiteDatabase: Failed to open database '/data/data/co.rez.myapplication/databases/northwind.db'. 
    android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database 
    at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method) 
    at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209) 
    at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193) 
    at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463) 
    at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185) 
    at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177) 
    at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804) 
    at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789) 
    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694) 
    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669) 
    at com.readystatesoftware.sqliteasset.SQLiteAssetHelper.getReadableDatabase(SQLiteAssetHelper.java:264) 
    at co.rez.myapplication.MyDatabase.getEmployees(MyDatabase.java:16) 
    at co.rez.myapplication.MainActivity.onCreate(MainActivity.java:13) 
    at android.app.Activity.performCreate(Activity.java:5326) 
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1090) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2233) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2319) 
    at android.app.ActivityThread.access$1100(ActivityThread.java:135) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1232) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:136) 
    at android.app.ActivityThread.main(ActivityThread.java:5234) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:931) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747) 
    at dalvik.system.NativeStart.main(Native Method) 
    07-21 11:18:52.250 16244-16244/co.rez.myapplication W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x41980c50) 
    07-21 11:18:55.180 16244-16244/co.rez.myapplication I/Process: Sending signal. PID: 16244 SIG: 9 

Answer 1

убедитесь, что папка Asset сделаны из студии, как этот

new -> folder -> assets 

, а также убедитесь, что northwind.db или northwind.sqlite (рекомендуется) в активах.

Answer 2

Убедитесь, что вы правильно

1. Скопируйте и вставьте northwind.db.zip файл внутри активов/баз данных папку.
2. Папка базы данных внутри активы папка.

Вы можете проверить шаг за шагом, как в очередной раз

android-sqlite-asset-helper