会议室使用日期字段 [英] Room Using Date field

问题描述

我正在使用日期转换器类来转换我的日期对象。但是，我仍然遇到一个错误的说法。错误：无法弄清楚如何将该字段保存到数据库中。您可以考虑为其添加类型转换器。

I am using date converter class to convert my date object. However, I still encounter an error saying. error: Cannot figure out how to save this field into a database. You can consider adding a type converter for it.

我的日期转换器类

public class DateConverter {

    @TypeConverter
    public static Date toDate(Long dateLong){
        return dateLong == null ? null: new Date(dateLong);
    }

    @TypeConverter
    public static long fromDate(Date date){
        return date == null ? null :date.getTime();
    }
}

我的数据库表中使用日期对象。

@Entity(tableName = "userFitnessDailyRecords")

    @TypeConverters(DateConverter.class)
    public class UserFitnessDailyRecords {

        @NonNull
        @PrimaryKey(autoGenerate = true)
        public int id;
        public Date forDay;

        public Date getForDay() {
            return forDay;
        }

        public void setForDay(Date forDay) {
            this.forDay = forDay;
        }
    }

我遵循了Google代码持久性实验室和commonwares室各自的GitHub示例。我正在使用1.0.0版的会议室。

I followed the example from google code persistence labs and from commonwares room respective GitHub example. I am using room version 1.0.0.

推荐答案

您正在从Date转换为 Long （包装器），并从 long （原始）至今。我将其更改为Long并进行了编译。

You're converting from Date to Long (wrapper) and from long (primitive) to Date. I changed it to Long and it compiled. Besides, unboxing null in your converter produces a NPE.

public class DateConverter {

    @TypeConverter
    public static Date toDate(Long dateLong){
        return dateLong == null ? null: new Date(dateLong);
    }

    @TypeConverter
    public static Long fromDate(Date date){
        return date == null ? null : date.getTime();
    }
}

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