java Joda LocalDate 到 LocalDateTime
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Joda LocalDate To LocalDateTime
提问by Suganthan Madhavan Pillai
I am trying to convert Joda LocalDateto Joda LocalDateTime, for that I am using the method toLocalDateTime(LocalTime.MIDNIGHT), as of now it is working
fine for example: for the given joda Localdate 2025-02-28I getting the expected joda LocalDateTime 2025-02-28T00:00:00.000, But my fear is, whether this method works fine at all situation. For example during dayLight savingtime zone anomalies..etc..
我正在尝试转换Joda LocalDate为Joda LocalDateTime，因为我正在使用该方法toLocalDateTime(LocalTime.MIDNIGHT)，到目前为止它工作正常，例如：对于给定的 joda Localdate2025-02-28我得到了预期的 joda LocalDateTime 2025-02-28T00:00:00.000，但我担心的是，这种方法是否在所有情况下都能正常工作. 例如during dayLight savingtime zone anomalies..等..
Update:I did a small research on this question, here it is
更新：我对这个问题做了一个小研究，这里是
toLocalDateTime(LocalTime time)Documentationsaying that: Converts LocalDate object to a LocalDateTime with LocalTimeto fill in the missing fields.
toLocalDateTime(LocalTime time)文档说：将 LocalDate 对象转换为 LocalDateTimeLocalTime以填充缺少的字段。
As I initializing LocalTimewith LocalTime.MIDNIGHT, from hereLocalTime.MIDNIGHTis a static final field initialized to new LocalTime(0, 0, 0, 0);, you can see that it is a time values are hardcode to zero values with ISOChronology getInstanceUTC(), so I think I will get the required output without any issue.
当我用 初始化LocalTime时LocalTime.MIDNIGHT，这里LocalTime.MIDNIGHT是一个初始化为 的静态最终字段new LocalTime(0, 0, 0, 0);，您可以看到这是一个时间值被硬编码为零值ISOChronology getInstanceUTC()，所以我想我会毫无问题地获得所需的输出。
回答by Ortomala Lokni
From the documentation, we know that
从文档中，我们知道
LocalDate is an immutable datetime class representing a date without a time zone.
LocalDateTime is an unmodifiable datetime class representing a datetime without a time zone.
Internally, LocalDateTime uses a single millisecond-based valueto represent the local datetime. This value is only used internally and is not exposed to applications.
Calculations on LocalDate are performed using a Chronology. This chronology will be set internally to be in the UTC time zone for all calculations.
LocalDate 是一个不可变的日期时间类，表示没有时区的日期。
LocalDateTime 是一个不可修改的日期时间类，表示没有时区的日期时间。
在内部，LocalDateTime 使用一个基于毫秒的值来表示本地日期时间。此值仅在内部使用，不会向应用程序公开。
LocalDate 的计算是使用 Chronology 进行的。此年表将在内部设置为所有计算的 UTC 时区。
We also know that the toLocalDateTimemethod of LocalDateclass is implemented like this:
我们也知道，toLocalDateTime方法LocalDate类等来实现此：
public LocalDateTime toLocalDateTime(LocalTime time) {
if (time == null) {
throw new IllegalArgumentException("The time must not be null");
}
if (getChronology() != time.getChronology()) {
throw new IllegalArgumentException("The chronology of the time does not match");
}
long localMillis = getLocalMillis() + time.getLocalMillis();
return new LocalDateTime(localMillis, getChronology());
}
Considering also that UTC has no Daylight saving time, we can conclude that you don't have to fear daylight saving problems nor time zone anomalies using the toLocalDateTimemethod because this method dont deal with timezones.
还考虑到UTC 没有夏令时，我们可以得出结论，您不必担心使用该toLocalDateTime方法的夏令时问题或时区异常，因为该方法不处理时区。
