@Database(entities = {Task.class}, version = 1)
public abstract class TaskDatabase extends RoomDatabase {
    public abstract TaskDao getTaskDao();
    private static volatile TaskDatabase instance;

    static synchronized TaskDatabase getInstance(Context context) {
        if (instance == null) {
            instance = create(context);
        }
        return instance;
    }

    public static TaskDatabase create(final Context context){
        return Room.databaseBuilder(
                context,
                TaskDatabase.class,
                "tasks_database").build();
    }
}