代码如下:
void main() {
Map<String, Map<String, int>> numsList = {
"1": {"appeared": 1},
"2": {"appeared": 2},
"3": {"appeared": 3},
"4": {"appeared": 9},
"5": {"appeared": 5},
};
int? maxAppearedValue = numsList.values
.map((e) => e["appeared"])
.reduce((a, b) => a! > b! ? a : b);
print(maxAppearedValue);
}
利用map遍历numList里的每个value,然后通过reduce里的逻辑来获取最大的value(对map本身并无影响)