how to iterate the list and build tree - flutter

Question

i have two cards in in row and each time row creates with two card i have data in my list and when list iterates it creates same name of card
i have an array of subcatextra and SubCategory class that have data i want to show first object name sub.name on first card and on second card name should be the next object of subcatextra list , i don't know how to achieve this please ** help me ***
here is my code
ListView(
children: subcatextra.map<Widget>((SubCategory sub)
{
return Row(
children: <Widget>[
Container(
width: (MediaQuery
.of(context)
.size
.width / 2) - 20,
height: 90,
child: InkWell(
onTap: (){},
child: Card(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8.0),
),
elevation: 1,
child: Container(
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
Container(
height: 70,
width: 80,
child: Image.network(
"https://smartbasket.pk/image/cache/data/Bazaarapna/dairy%20product/Haleeb%20Milk%20%E2%80%93%2001%20Litre%20(Pack%20of%2012)-500x500.jpg",
fit: BoxFit.cover)),
Container(margin: EdgeInsets.only(right: 15),
child: Text(sub.name, style: TextStyle(fontSize: 17),))
],
),
),
),
),
),
Spacer(),
Container(
width: (MediaQuery
.of(context)
.size
.width / 2) - 20,
height: 90,
child: Card(
elevation: 1,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(8.0),
),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
Container(
height: 70,
width: 80,
child: Image.network(
"https://smartbasket.pk/image/cache/data/Bazaarapna/dairy%20product/Haleeb%20Milk%20%E2%80%93%2001%20Litre%20(Pack%20of%2012)-500x500.jpg",
fit: BoxFit.cover)),
Text(sub.name, style: TextStyle(fontSize: 17),)
],
),
),
)
],
);
}).toList()
);

Answer 1

You can use a ListView.builder, create two variables for each object and assign them according the index being even or odd. Bellow follows a complete example that you cant test at DartPad:
import 'package:flutter/material.dart';
void main() {
runApp(MaterialApp(home: CardListView()));
}
class CardListView extends StatefulWidget {
#override
_CardListViewState createState() => _CardListViewState();
}
class _CardListViewState extends State<CardListView> {
#override
void initState() {
super.initState();
}
List<String> list = [
'name1',
'name2',
'name3',
'name4',
'name5',
'name6',
'name7',
];
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("Title")),
body: new ListView.builder(
itemCount: list.length,
itemBuilder: (BuildContext ctxt, int index) {
String firstCellContent = '';
String secondCellContent = '';
if (index % 2 == 0) {
firstCellContent = list[index];
if (index + 1 < list.length - 1) {
secondCellContent = list[index + 1];
} else {
secondCellContent = '';
}
}
return Row(
children: <Widget>[
Container(
padding: EdgeInsets.all(15),
child: new Text(
firstCellContent,
),
),
Container(
padding: EdgeInsets.all(15),
child: new Text(
secondCellContent,
),
),
],
);
},
),
);
}
}