无法从 DAO 解析方法

Question

我正在使用 Room Library 尝试一个简单的数据库示例。我有一个闹钟 class

@Entity
public class Alarm{

    @PrimaryKey
    public int id;
    public long alarmtime;

    public Alarm(int id, long alarmtime){
        this.id = id;
        this. alarmtime = alarmtime;
    }

}

一个AlarmDAO接口，

@Dao
public interface AlarmDAO {

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void addAlarm(Alarm alarm);

    @Query("select * from Alarm")
    public List<Alarm> getAllAlarm();

    @Query("select * from Alarm where id = :id")
    public List<Alarm> getAlarm(long userId);

    @Update(onConflict = OnConflictStrategy.REPLACE)
    void updateAlarm(Alarm alarm);

    @Query("delete from Alarm")
    void removeAllAlarm();

    }

还有一个报警数据库class,

@Database(entities = {Alarm.class}, version = 16, exportSchema = false)
    public abstract class AlarmDatabase extends RoomDatabase {

        private static AlarmDatabase INSTANCE;

        public abstract Alarm AlarmDAO();

        public static AlarmDatabase getDatabase(Context context) {
            if (INSTANCE == null) {
                INSTANCE =
                        Room.databaseBuilder(context, AlarmDatabase.class, "userdatabase")
                                .allowMainThreadQueries()//remove this line in production
                                .fallbackToDestructiveMigration()
                                .build();
            }
            return INSTANCE;
        }
}

在 MainActivity 中，当我尝试从 AlarmDAO 访问一个方法时，它说它无法解析该方法，

database = AlarmDatabase.getDatabase(this);
database.AlarmDAO().removeAllAlarm();

Answer 1

您在 AlarmDatabase 中没有名为 AlarmDao 的字段。您有一个名为 AlarmDAO() 的方法。因此，调用 AlarmDAO() 方法：

database.AlarmDAO().removeAllAlarm();

Answer 2

分析了我所有的代码后，我意识到我使用了将 AlarmDAO 分配给 Alarm （我不知道为什么可以接受，因为它们属于不同类型）所以改变这个在 AlarmDatabase.java 中使其开始工作。

@Database(entities = {Alarm.class}, version = 16, exportSchema = false)
    public abstract class AlarmDatabase extends RoomDatabase {

    private static AlarmDatabase INSTANCE;

    public abstract AlarmDAO AlarmDAO();// WAS originally Alarm AlarmDAO();

    public static AlarmDatabase getDatabase(Context context) {
...

无法从 DAO 解析方法

Cannot resolve Method from DAO

android

android-room