flutter - 如何仅更改DateTime中的时间？

Question

我有一个DateTime，我正在尝试用它做两件事。 1:仅更新日期和月份。 2:仅更新时间。我该如何实现？

  DateTime currentDateTime = DateTime.now();

  void updateTime(DateTime newTime) {
       currentDateTime = ?
  }
  void updateDate(DateTime newTime) {
       currentDateTime = ?
  }

有什么办法可以破坏 currentDateTime像 DateTime(...currentDateTime, ..newTime)

Answer 1

从Datetime.now()属性而不是整个Datetime.now()对象构造Datetime对象。这应该工作。

  DateTime currentDateTime = DateTime.now();

  void updateTime(DateTime currentDateTime, DateTime newTime) {
       currentDateTime = DateTime(
         year: currentDateTime.year,
         month: currentDateTime.month
         day: currentDateTime.day,
         hour: newTime.hour,
         minute: newTime.minute,
         second: newTime.second,
       );
  }

  void updateDate(DateTime currentDateTime, DateTime newDate) {
       currentDateTime = DateTime(
         year: currentDateTime.year,
         month: newTime.month
         day: newTime.day,
         hour: currentDateTime.hour,
         minute: currentDateTime.minute,
         second: currentDateTime.second,
       );
  }

记住Datetime的构造函数看起来像这样

DateTime(int year, [int month = 1, int day = 1, int hour = 0, int minute = 0, int second = 0, int millisecond = 0, int microsecond = 0])