Question

我想更新地图内的数组

Map<int, List<String>> testtable = {
    1: ['a', 'b', 'c', 'e'],
    2: ['f', 'g', 'h', 'j'],
  };

我想在 key = 1 的数组中更新 e => d，

我试过这个 testtable.update(1, (list[3]) => d); 但没有用

Answer 1

你可以这样做：

testtable.update(
  1,
  (value) {
    value[3] = 'd';
    return value;
  },
);

Answer 2

update 期望新值作为参数，因此您必须返回整个列表。

testtable.update(1, (list) {
    list[3] = 'd';
    return list;
});

Answer 3

另一种选择：

void main() {
  Map<int, List<String>> testtable = {
    1: ['a', 'b', 'c', 'e'],
    2: ['f', 'g', 'h', 'j'],
  };
  
  print (testtable);
  
  testtable[1][3]='d';
  print (testtable);
}

Answer 4

更新嵌套地图

 Map<String, Map> selectedTimes = {
    "monday": {"open": "7:30 AM", "close": "10:30 AM"},
    "tuesday": {"open": "7:30 AM", "close": "10:30 AM"},
    "wednesday": {"open": "7:30 AM", "close": "10:30 AM"},
    "thursday": {"open": "7:30 AM", "close": "10:30 AM"},
    "friday": {"open": "7:30 AM", "close": "10:30 AM"},
    "saturday": {"open": "7:30 AM", "close": "10:30 AM"},
    "sunday": {"open": "7:30 AM", "close": "10:30 AM"}
  };


selectedTimes.update(day, (list) {
  list.update(
      time, (value) => selectedTimeRTL!.format(context).toString());
  return list;
})

如何在颤振中更新地图内数组的数据

4 个答案: