List<Map<String, dynamic>> map= [ { 'amount': 200, 'name': "James", 'id': "1df" }, { 'amount': 300, 'name': "Joseph", 'id': "2df" }, { 'amount': 400 ,'name': "Joe" ,'id': "3df" }, ];
  map.sort((a, b) => b['amount'].compareTo(a['amount']));
  print(map[0]);

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如果您不想打乱您原始Map顺序，请创建一个临时Map并对其进行排序以获得您所需的元素。

保持列表顺序

List<Map<String, dynamic>> bids= [ { 'amount': 200, 'name': "James", 'id': "1df" }, { 'amount': 300, 'name': "Joseph", 'id': "2df" }, { 'amount': 400 ,'name': "Joe" ,'id': "3df" }, ];

if (bids.isNotEmpty) {
var max = bids[0];
bids.forEach((item) {
if (item['amount'] > max['amount']) max = item;
});
print(max['amount']);
print(bids);
}

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输出

的数据

根据这个猜测What is the algorithm used in sort method in dart?，Dart List.sort的时间复杂度为O(nLog(n))
你可以用O(N)的时间复杂度（更快）和恒定的内存复杂度来实现这一点，而不需要改变你的初始列表，如下所示：

void main() {
    double maxBid = getMaxBid([
      {'amount': 200, 'name': "James", 'id': "1df"},
      {'amount': 300, 'name': "Joseph", 'id': "2df"},
      {'amount': 400, 'name': "Joe", 'id': "3df"},
    ]);
    print("Max Bid is $maxBid");
  }

  double getMaxBid(List<Map<String, dynamic>> bids) {
    double maxBid = -double.infinity; // or zero depending on your bid range
    for (var bid in bids) {
      double bidAmount = bid["amount"];
      if (bidAmount <= maxBid) continue;
      maxBid = bidAmount;
    }
    return maxBid;
  }

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