Flutter: Help building a scrollable ListView - flutter

Question

item1, item2, item3 are all lists and i am trying to build a list view with all the items that each list holds, where all this three listview builders would take as much place as they need, lets say that item1 has 20 items in it and it will take 20 rows, and item2 has 25 etc. When i try to use a row and listview.builder it gives me an error.
What I am trying to do:
body: Container(
child: Column(
children: <Widget>[
Row(
children: <Widget>[
ListView.builder(
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(widget.item1[index]),
);
},
itemCount: widget.item1 == null ? 0 : widget.item1.length,
),
],
),
],
),
),
Among a huge list of crash report:
flutter: Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
flutter: Another exception was thrown: NoSuchMethodError: The getter 'visible' was called on null.
The problem is that the only way I know is to make it with an Expanded, and it will divide the screen in three and make equal space or i can manipulate with flex, but this is not what i want.
body: Container(
child: Column(
children: <Widget>[
Expanded(
child: ListView.builder(
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(widget.item1[index]),
);
},
itemCount: widget.item1 == null ? 0 : widget.item1.length,
),
),
Expanded(
child: ListView.builder(
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(widget.item2[index]),
);
},
itemCount: widget.item2 == null ? 0 : widget.item2.length,
),
),
Expanded(
child: ListView.builder(
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(widget.item3[index]),
);
},
itemCount: widget.item3 == null ? 0 : widget.item3.length,
),
),
],
),
),

Answer 1

This is what I was talking about, a List using SingleChildScrollView and Column, you can also do the same with Slivers
A sample I made for you:
final List<String> item1 = List.generate(5, (val) => "item1 $val");
final List<String> item2 = List.generate(5, (val) => "item2 $val");
final List<String> item3 = List.generate(5, (val) => "item3 $val");
#override
Widget build(BuildContext context) {
final items = <Widget>[];
for (String i1 in item1) {
items.add(ListTile(
title: Text(i1),
));
}
for (String i2 in item2) {
items.add(ListTile(
title: Text(
i2,
style: TextStyle(
color: Colors.red,
),
),
));
}
for (String i3 in item3) {
items.add(ListTile(
title: Text(
i3,
style: TextStyle(
color: Colors.blue,
),
),
));
}
return Scaffold(
body: Container(
child: SingleChildScrollView(
child: Column(
children: items,
),
),
),
);
}
}
Another way using ListView.builder :
return Scaffold(
body: Container(
child: SingleChildScrollView(
child: Column(
children: [
ListView.builder(
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(item1[index]),
);
},
itemCount: item1.length,
),
ListView.builder(
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(
item2[index],
style: TextStyle(
color: Colors.red,
),
),
);
},
itemCount: item2.length,
),
ListView.builder(
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(item3[index]),
);
},
itemCount: item3.length,
),
],
),
),
),
);
}
Don't forget to check this awesome article about Slivers by Emily Fortuna (Flutter team)
https://medium.com/flutter/slivers-demystified-6ff68ab0296f