Flutter setState not update Widget

Question

I have a function called showdialog and, for some reason, numberPicker does not update its value in showdialog. I know you can use NumberPickerDialog but I would like to know how to solve it in this case. When I use the numberPicker outside the showdialog it works normally

List intList = [0,0,0,0,0,0];
    
    Scaffold(
          appBar: AppBar(),
          body: Center(child: ListView.builder(
            itemCount: list.length,
            itemBuilder: (context, index){
              return Container(child: IconButton(
                icon: Icon(Icons.alarm),
                onPressed: (){
                  _showdialog(index: index);
                },
              ));
            } ),
        ));
      }
       _showdialog({int index, int value}){
      showDialog<int>(
          barrierColor: Colors.black54,
          context: context,
          builder: (BuildContext context){
            return  AlertDialog(
             content: 
             FutureBuilder(
               future: future,
               builder: (context, snapshot) =>  
              NumberPicker.integer(
                  initialValue: intList[index],
                  minValue: 00,
                  maxValue: 23,
                  onChanged: (value){
                    setState(() {
                      intList[index] = value;
                    });
                  },
                )));
          }
        );
      }