Flutter-从List.map()获取迭代索引 [英] Flutter - Get iteration index from List.map()
问题描述
我在网上搜索了很多答案。
I searched alot on net for answer.
我在字母列表上编写了迭代,并使用地图
类在屏幕上放置了卡片
I wrote iteration on list of letters and put inside cards on screen using "map" class
在代码中,您可以看到我做了一行,并使用 map在卡片上的所有userBoard上都打印到了屏幕上。
我想在里面添加一些逻辑,所以我需要获取元素的ID(用于Taping事件)。
有什么方法可以做到?
In the code you can see that i made a row and using "map" printed aall the userBoard on cards to the screen. I want to add some logics inside so i need to gett the id of the elemnt (for taping event). Theres a way that i can do taht?
实际上我想通过userBoard获取特定的元素索引
Actually i want to get a specific index of element over userBoard
代码:
Widget build(BuildContext context) {
return Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
Row(
children: userBoard
.map((element) => Stack(children: <Widget>[
Align(
alignment: Alignment(0, -0.6),
child: GestureDetector(
onTap: (() {
setState(() {
// print("element=${element.toString()}");
// print("element=${userBoard[element]}");
});
}),
child: SizedBox(
width: 40,
height: 60,
child: Card(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(5.0),
),
child: Center(
child: Text(element,
style: TextStyle(fontSize: 30)),
)),
),
),
)
]))
.toList(),
)
],
),
}
Picture - each card is "element" of the map. I want to get the indexes for the function onTap.
谢谢。
推荐答案
要访问索引,您需要使用 asMap 运算符。
To get access to index, you need to convert your list to a map using the asMap operator.
示例
final fruitList = ['apple', 'orange', 'mango'];
final fruitMap = myList.asMap(); // {0: 'apple', 1: 'orange', 2: 'mango'}
// To access 'orange' use the index 1.
final myFruit = fruitMap[1] // 'orange'
// To convert back to list
fruit fruitListAgain = fruitMap.values.toList();
您的代码
userBoard.asMap().map((i, element) => MapEntry(i, Stack(
GestureDetector(onTap: () {
setState(() {
// print("element=${element.toString()}");
// print("element=${userBoard[i].toString()}");
});
}),
))).values.toList();
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