Android Room Persistence Library TypeConverter 未知问题

Question

我很难将我的实体保存到房间持久性数据库中。据我了解，RPL（RoomPersistenceLibrary）将只接受原始类型，所以我需要将我的两个字段：Calendar mStartDate、Calendar mEndTime 转换为使用 Typeconverters 的字符串（这两个字段都用于设置开始和结束日期 - 分钟、小时,day,month,year 每次我创建 WeekViewEvent's - 请参阅构造函数。

所以我创建了一个，但它仍然有问题，因为 Android Studio 不断向我显示相同的错误： 无法弄清楚如何将此字段保存到数据库中（..） 由于控制台不显示代码行，我无法追踪错误。

有什么想法我可能做错了吗？ 预先感谢您的任何帮助！ :)

WeekViewEvent.class：

@Entity
public class WeekViewEvent implements Serializable {

@NonNull
@PrimaryKey
private long mId;
private String mName;
private String mLocation;
private int mColor;
private boolean mAllDay;
private Shader mShader;
private String Identifier;

@TypeConverters({WeekViewEventCONVERTER.class})
private Calendar mStartTime;
@TypeConverters({WeekViewEventCONVERTER.class})
private Calendar mEndTime;


public WeekViewEvent(long id, String name, String location, String identifier, int color, int startYear, int startMonth, int startDay, int startHour, int startMinute, int endYear, int endMonth, int endDay, int endHour, int endMinute) {
    this.mId = id;
    this.mStartTime = Calendar.getInstance();
    this.mStartTime.set(Calendar.YEAR, startYear);
    this.mStartTime.set(Calendar.MONTH, startMonth - 1);
    this.mStartTime.set(Calendar.DAY_OF_MONTH, startDay);
    this.mStartTime.set(Calendar.HOUR_OF_DAY, startHour);
    this.mStartTime.set(Calendar.MINUTE, startMinute);
    this.mEndTime = Calendar.getInstance();
    this.mEndTime.set(Calendar.YEAR, endYear);
    this.mEndTime.set(Calendar.MONTH, endMonth - 1);
    this.mEndTime.set(Calendar.DAY_OF_MONTH, endDay);
    this.mEndTime.set(Calendar.HOUR_OF_DAY, endHour);
    this.mEndTime.set(Calendar.MINUTE, endMinute);
    this.mName = name;
    this.Identifier = identifier;
    this.mLocation = location;
    this.mColor = color;}
...
}

WeekViewEventCONVERTER.class：

 @TypeConverter
public static Calendar fromString (String value){
    Type calendarType = new TypeToken<Calendar>() {}.getType();
    return new Gson().fromJson(value, calendarType);
}

@TypeConverter
public static String fromCalendar (Calendar mStartTime){
    Gson gson = new Gson();
    String json = gson.toJson(mStartTime);
    return json;
}

}

和 WeekViewEventDAO：

@Dao
public interface WeekViewEventDAO {

@Insert(onConflict = OnConflictStrategy.REPLACE)
public long insertWeekViewEvent (WeekViewEvent event);

@Update(onConflict = OnConflictStrategy.REPLACE)
public void updateWeekViewEvent (WeekViewEvent event);

@Delete
public void deleteWeekViewEvent (WeekViewEvent event);

@Query("DELETE FROM WeekViewEvent")
public void deleteAllWeekViewEvents();

@Query("SELECT * FROM WeekViewEvent")
WeekViewEvent getWeekViewEvent();

@Query("SELECT * FROM WeekViewEvent")
public List<WeekViewEvent> getAllWeekVieweventsList();}

Answer 1

我认为您的问题是您没有此字段的类型转换器：

private Shader mShader;

尝试添加@Ignore 将其标记为非持久性。