flutter tabbar swippable issue - flutter

Question

i am newbie to flutter and i created a tab bar and tab bar view by adding dynamic content as following code. when click on tab in tab bar it works fine. but swiping tab bar view new value always detect on another swipe for example move to tab one tab bar view says 0. move to tab 2 tab bar view says 1.
please help me friends.
#override
void initState() {
super.initState();
setState(() {
_isLoading = true;
num = 0;
for(int i=0;i<3;i++){
_tabs.add(Tab(text: '${i + 1}'));
tabView.add(getWidget());
}
_tabController = TabController(vsync: this, length: _tabs.length, initialIndex: 0);
_tabController.addListener((){
print('index${_tabController.index}');
setState(() {
num = _tabController.index ;
});
});
Widget getWidget(){
return Builder(builder: (BuildContext context) {
return Text('${num}');
});
}
#override
Widget build(BuildContext context) {
return
DefaultTabController(
length: _tabs.length,
child:Scaffold(
appBar: AppBar(
title: Text("cart"),
bottom: TabBar(
controller: _tabController,
tabs: _tabs,
),
),
body: TabBarView(
controller: _tabController,
children:tabView,
),
});

Answer 1

Use AutomaticKeepAliveClientMixin
override wantKeepAlive property and return true
Instead of this:
tabView.add(getWidget());
use:
tabView.add(Tabpageview(TabData(i)));
class Tabpageview extends StatefulWidget {
final tabData;
Tabpageview(this.tabData);
#override
_TabpageviewState createState() => _TabpageviewState();
}
class _TabpageviewState extends State<Tabpageview>
with AutomaticKeepAliveClientMixin {
#override
bool get wantKeepAlive => true;
#override
Widget build(BuildContext context) {
super.build(context);
return Tab(child: Center(child: Text('Tab : ${widget.tabData.data}')));
}
}
class TabData {
int data;
TabData(this.data);
}

Answer 2

Modify your code with some smooth animation, plz modify setState() method as per your need.
final aniValue = _tabController.animation.value;
if (aniValue > 0.5 && index != 1) {
products.forEach((item) {
setState(() {
displayProducts.add(item);
});
});
} else if (aniValue <= 0.5 && index != 0) {
products.forEach((item) {
setState(() {
displayProducts.add(item);
});
});
}