這是我的代碼
final _months = [
["January", "Febuary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"]
];
......
DropdownButtonFormField(
hint: const Text('Select Period'),
items: _months.map((e) {
return DropdownMenuItem(
value: e,
child: Text(e //here is the error showing),
);
}).toList(),
onChanged: (value) {
//do something
},
),
如何解決這個問題，我只是將月份映射值從 dfault 更改為動態，然后錯誤消失了，但是當我運行應用程式時，它顯示另一個錯誤，例如“這不是字串的子型別”如何解決這個問題以及為什么是這發生
uj5u.com熱心網友回復：
你有一組額外的[ ]所以你的_months變數是型別List<List<String>>：
final _months = ["January", "Febuary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
uj5u.com熱心網友回復：
你有陣列里面的陣列：正確的是：
final _months = [
"January", "Febuary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"
];
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