how to load database path from access folder in android studio?

i've a database sqlite copy into access folder in android studio. i create class DatabaseHelper and methods check and copy db. but when build project on my phone, there is no database. pls help me? this is my code in class DatabaseHelper.java .

public class DatabaseHelper extends SQLiteOpenHelper {
private static String DB_PATH = "";
private static String DB_NAME = "my_sqlite.sqlite";
private String TAG = "TAG";
private SQLiteDatabase myDataBase;
private final Context myContext;

public DatabaseHelper(Context context) {
    super(context, DB_NAME, null, 1);
    if (Build.VERSION.SDK_INT >= 17) {
        DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
    } else {
        DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
    }
    this.myContext = context;
}

@Override
public void onCreate(SQLiteDatabase db) {

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

@Override
public synchronized void close() {
    if (myDataBase != null)
        myDataBase.close();
    super.close();
}

//kiem tra database neu ton tai thi thong bao database san dang su dung
//neu khong thi copy database vao duong dan "DB_PATH+DB_NAME"
public void checkAndCopyDatabase() {
    boolean dbExist = checkDataBase();
    if (dbExist) {
        Log.d(TAG, "database already exist!");
    } else {
        this.getReadableDatabase();
        try {
            copyDatabase();
        } catch (IOException e) {
            Log.d(TAG, "Error copying database");
        }
    }
}

public boolean checkDataBase() {
    SQLiteDatabase checkDB = null;
    try {
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
    } catch (SQLiteException e) {
    }
    if (checkDB != null) checkDB.close();
    return checkDB != null ? true : false;
}

public void copyDatabase() throws IOException {
    InputStream myInput = myContext.getAssets().open(DB_NAME);
    String outFileName = DB_PATH + DB_NAME;
    OutputStream myOutput = new FileOutputStream(outFileName);
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }
    myOutput.flush();
    myOutput.close();
    myInput.close();
}

public void openDataBase() throws SQLException {
    String myPath = DB_PATH + DB_NAME;
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}

public void ExeSQLData(String sql) throws SQLException {
    myDataBase.execSQL(sql);
}

public Cursor QueryData(String query) throws SQLException {
    return myDataBase.rawQuery(query, null);
}

}