How to stop a widget to reload on setState() method in StatefulWidget Class in Flutter

Build it in initState() then use it's reference wherever required it will not build again until parent widget reinitialized.

  var banner;  @override  void initState() {    // TODO: implement initState    super.initState();    bannerSize = AdmobBannerSize.BANNER;    banner = AdmobBannerWrapper(adUnitId: getBannerAdUnitId(),adSize: bannerSize,key:_globalKey,);  }

than call it in by reference here banner

  @override  Widget build(BuildContext context) {    double height = MediaQuery.of(context).size.height;    double width = MediaQuery.of(context).size.width;    return new Scaffold(      body: new Container(          width: width,          child: new Center(            child: Column(              mainAxisAlignment: MainAxisAlignment.end,              children: <Widget>[                Expanded(                  child: Column(                    mainAxisAlignment: MainAxisAlignment.center,                    mainAxisSize: MainAxisSize.max,                    children: <Widget>[                      Flexible(                        child: new Hero(                          tag: "gender",                          child: Material(                            child: new Row(                              children: <Widget>[                                InkWell(                                  onTap: () {                                    setState(() {                                      if (isFemaleSelected) {                                        isFemaleSelected = false;                                      } else {                                        isFemaleSelected = true;                                      }                                    });                                  },                                  child: Opacity(                                    child: Image.asset(                                      "assets/woman.png",                                      height: height / 4,                                      width: width / 2 - 12,                                    ),                                    opacity: isFemaleSelected ? 1.0 : 0.30,                                  ),                                ),                                InkWell(                                  onTap: () {                                    setState(() {                                      if (isFemaleSelected) {                                        isFemaleSelected = false;                                      } else {                                        isFemaleSelected = true;                                      }                                    });                                  },                                  child: Opacity(                                    opacity: !isFemaleSelected ? 1.0 : 0.30,                                    child: Image.asset(                                      "assets/boy.png",                                      height: height / 4,                                      width: width / 2 - 12,                                    ),                                  ),                                ),                              ],                            ),                          ),                        ),                      ),                    ],                  ),                  flex: 1,                ),                InkWell(                    onTap: () {                      setState(() {                      });                      Navigator.push(                          context,                          MaterialPageRoute(                              builder: (BuildContext) =>                                  new HeightWeightSelection(isFemaleSelected                                      ? "assets/woman.png"                                      : "assets/boy.png")));                    },                    child: Container(                      margin: EdgeInsets.only(bottom: 12.0),                      child: new Image.asset(                        "assets/next.png",                        height: 64.0,                        width: 64.0,                      ),                    )),                banner, /*this is our variable */               /* new AdmobBanner(                  adUnitId: getBannerAdUnitId(),                  adSize: bannerSize,                  listener:                      (AdmobAdEvent event, Map<String, dynamic> args) {                    handleEvent(event, args, 'Banner');                  },                ),*/              ],            ),          )),    );  }

Put it inside a stateless widget:

class AdBanner extends StatelessWidget{  final adUnitId;  final adSize;  const AdBanner({Key key, this.adUnitId, this.adSize}) : super(key: key);  Widget build(BuildContext context){    return AdmobBannerWrapper(      adUnitId: getBannerAdUnitId(),      adSize: bannerSize,      key: _globalKey,      );  }}

next time when you call setState if the parameters are unchanged, it is not going to get rebuilt.