[Dart]DateTime型についてメモ

はじめに

未経験からエンジニアに転職して4ヶ月ほど経ちました。
毎日壁にぶつかりながらも楽しく働いています。

普段はrailsを扱っていますが、最近Flutterも触ってみたいなーと思って休日はDartを勉強しております。

今回はDateTime型について学んだのでアウトプットしていきます。

現在時刻を取得する

DateTime now = DateTime.now();
now;//2022-07-23 21:24:04.916

指定する

DateTime date = DateTime(2021,7,3,21,20,20,111);
date;//2021-07-03 21:20:20.111

年や月、日等を取得する

DateTime now = DateTime.now();
now;//2022-07-23 22:21:21.950
now.year;//2022
now.month;//7
now.day;//23
now.hour;//22
now.minute;//21
now.second;//21
now.millisecond;//950

addメソッド(加算する)

DateTime now = DateTime.now();
now;//2022-07-23 22:58:05.875
now.add(Duration(days: 1));//2022-07-24 22:58:05.875
now.add(Duration(days: -1));//2022-07-22 22:58:05.875

subtractメソッド(減算する)

DateTime now = DateTime.now();
now;//2022-07-23 22:58:05.875  
now.subtract(Duration(days: 1));//2022-07-22 23:31:13.461
now.subtract(Duration(days: -1));//2022-07-24 23:31:13.461

compareToメソッド(比較する)

DateTime now = DateTime.now();
DateTime yesterday = now.subtract(Duration(days: 1));
DateTime tomorrow = now.add(Duration(days: 1));
  
now.compareTo(now);//0
now.compareTo(yesterday);//1
now.compareTo(tomorrow);//-1

isBeforeメソッド（未来か）

DateTime now = DateTime.now();
DateTime yesterday = now.subtract(Duration(days: 1));
DateTime tomorrow = now.add(Duration(days: 1));

print(now.isBefore(now));//false
print(now.isBefore(tomorrow));//true
print(now.isBefore(yesterday));//false

isAfterメソッド（過去か）

DateTime now = DateTime.now();
DateTime yesterday = now.subtract(Duration(days: 1));
DateTime tomorrow = now.add(Duration(days: 1));
now.isAfter(now);//false
now.isAfter(tomorrow);//false
now.isAfter(yesterday);//true

isAtSameMomentAsメソッド（同一か）

DateTime now = DateTime.now();
DateTime yesterday = now.subtract(Duration(days: 1));
DateTime tomorrow = now.add(Duration(days: 1));

now.isAtSameMomentAs(now);
now.isAtSameMomentAs(tomorrow);
now.isAtSameMomentAs(yesterday);

differenceメソッド（差分を取得）

DateTime now = DateTime.now();
DateTime yesterday = now.subtract(Duration(days: 1));
DateTime tomorrow = now.add(Duration(days: 1));

now.difference(yesterday).inDays;//1
now.difference(yesterday).inHours;//24
now.difference(yesterday).inMinutes;//1,440
now.difference(yesterday).inSeconds;//86,400

now.difference(tomorrow).inDays;//-1
now.difference(tomorrow).inHours;//-24
now.difference(tomorrow).inMinutes;//-1,440
now.difference(tomorrow).inSeconds;//-86,400

曜日や月の取得も出来る

DateTime.january;//1
DateTime.february;//2
DateTime.march;//3
DateTime.april;//4
DateTime.may;//5
DateTime.june;//6
DateTime.july;//7
DateTime.august;//8
DateTime.september;//9
DateTime.october;//10
DateTime.november;//11
DateTime.december;//12

DateTime.monday;//1
DateTime.tuesday;//2
DateTime.wednesday;//3
DateTime.thursday;//4
DateTime.friday;//5
DateTime.saturday;//6
DateTime.sunday;//7

まとめ

メソッド	何が出来る？する？
.now	現在時刻を取得
.year, .month, etc...	年や月を取得
.add	加算する
.subtract	減算する
.compareTo	比較
.isBefore	未来か
.isAfter	過去か
.isAtSameMomentAs	同一か
.difference	差分を取得

参考

読んで頂きありがとうございました!