Android sqlite asset helper cannot read my database

Question

I have trouble with reading my assets folder database using SQLite Asset Helper. I created a new test project with new database , but it didn't work again. here is my code:

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;
    }

}

I declared also WRITE_EXTERNAL_STORAGE permission. but app crashes. Can somebody help me? Thanks.

(edited) 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

Make sure you properly

1. Copy and paste the northwind.db.zip file inside the assets/databases folder.
2. folder databases inside the assets folder.

You can check step by step way once again

android-sqlite-asset-helper

Answer 2

make sure your Asset folder made from studio like this

new -> folder -> assets

and also make sure northwind.db or northwind.sqlite (recommended) is in assets.