FlutterのList<Map<String,dynamic>>をintやDateTimeでsortする

数字が大きい順

void sort() {
  final List<Map<String,dynamic>> list = [
    {'score': 1},
    {'score': 2},
    {'score': 3}
  ];
  list.sort((a,b) => b['score'].compareTo(a['score']));
  print(list);
}
  

結果

[{score: 3}, {score: 2}, {score: 1}]

数字が小さい順

void sort(){
  final List<Map<String,dynamic>> list = [
    {'score': 1},
    {'score': 2},
    {'score': 3}
  ];
  list.sort((a,b) => a['score'].compareTo(b['score']));
  print(list);
}

結果

[{score: 1}, {score: 2}, {score: 3}]

新しい順

void sort(){
  final firstDay = DateTime(2021,10,10);
  final nextDay = DateTime(2021,10,11);
  final nextNextDay = DateTime(2021,10,12);
  final List<Map<String,dynamic>> timeStamps = [
    {'createdAt': firstDay},
    {'createdAt': nextDay},
    {'createdAt': nextNextDay}
  ];
  timeStamps.sort((a,b) => b['createdAt'].compareTo(a['createdAt']));
  print(timeStamps);
}

結果

[{createdAt: 2021-10-12 00:00:00.000}, {createdAt: 2021-10-11 00:00:00.000}, {createdAt: 2021-10-10 00:00:00.000}]

古い順

void sort(){
  final firstDay = DateTime(2021,10,10);
  final nextDay = DateTime(2021,10,11);
  final nextNextDay = DateTime(2021,10,12);
  final List<Map<String,dynamic>> timeStamps = [
    {'createdAt': firstDay},
    {'createdAt': nextDay},
    {'createdAt': nextNextDay}
  ];
  timeStamps.sort((a,b) => a['createdAt'].compareTo(b['createdAt']));
  print(timeStamps);
}

結果

[{createdAt: 2021-10-10 00:00:00.000}, {createdAt: 2021-10-11 00:00:00.000}, {createdAt: 2021-10-12 00:00:00.000}]