Could Not Open Database In Android Studio

I've created G class in-order to using database but in first steps I got this error :

   Caused by: android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database

Also in AndroidManifest.xml I added :

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

This is my G class :

package com.example.n5110.database;
import android.app.Application;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.os.Environment;
import java.io.File;
public class G extends Application {
    public static Context context;
    public static SQLiteDatabase database;
    public static final String DIR_SDCARD = Environment.getExternalStorageDirectory().getAbsolutePath();
    public static final String DIR_DATABASE = DIR_SDCARD + "/database-test/";
    @Override
    public void onCreate() {
        super.onCreate();
        context = this.getApplicationContext();
        new File(DIR_DATABASE).mkdirs();
        database = SQLiteDatabase.openOrCreateDatabase(DIR_DATABASE + "/database.sqlite", null);
    }
}

Does anyone have an idea??