如何在传入变量时查询房间数据库的LiveData<String>

implementation "androidx.room:room-runtime:2.4.0"
annotationProcessor "androidx.room:room-compiler:2.4.0"

@Database(entities = {RoomEntity.class}, version = 1)
public abstract class MyRoomDatabase extends RoomDatabase {
    public abstract MyDao myDao();
}

@Dao
public interface MyDao {
    @Query("SELECT data FROM my_table WHERE id = :roomId")
    LiveData<String> getRoomData(String roomId);
}

public class MyViewModel extends ViewModel {
    private LiveData<String> roomData;

    public LiveData<String> getRoomData(String roomId) {
        if (roomData == null) {
            MyRoomDatabase database = Room.databaseBuilder(context, MyRoomDatabase.class, "my-db").build();
            roomData = database.myDao().getRoomData(roomId);
        }
        return roomData;
    }
}

public class MyActivity extends AppCompatActivity {
    private MyViewModel myViewModel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);

        myViewModel = new ViewModelProvider(this).get(MyViewModel.class);
        
        // 观察LiveData并在数据发生变化时进行响应
        myViewModel.getRoomData("roomId").observe(this, new Observer<String>() {
            @Override
            public void onChanged(String data) {
                // 处理数据变化
            }
        });
    }
}