change color of a box in list of boxes on tap flutter

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Tabbed()
    );
  }
}

class Tabbed extends StatefulWidget {
  @override
  _TabbedState createState() => _TabbedState();
}

class _TabbedState extends State<Tabbed> {
  Color color = Colors.green; 
  @override
  void initState() {
    for(int i=0;i<listLength;i++){
      list1.add(
      TabModel(isTapped: false)); // assigns initial value to false
    }
    for(int i=0;i<listLength;i++){
      list2.add(
      TabModel(isTapped: false)); // assigns initial value to false
    }
  }
  
  Widget column1(){
    return Column(
    children: List.generate(
          listLength,
          (index) =>GestureDetector(
          onTap: (){
            // this selects only one out of many and disables rest
            for(int i=0;i<list1.length;i++){
              if(i!=index){
                list1[i].isTapped=false;
              }
            };
            setState((){
              list1[index].isTapped = true;
            });
          },
          child:Container(
            margin:EdgeInsets.all(5),
            color: list1[index].isTapped? Colors.red:color,
          height:100,
          width:100
          ))
        ));
  }
  
  Widget column2(){
    return Column(
    children: List.generate(
          listLength,
          (index) =>GestureDetector(
          onTap: (){
            setState((){
              list2[index].isTapped = !list2[index].isTapped;
            });
          },
          child:Container(
            margin:EdgeInsets.all(5),
            color: list2[index].isTapped? Colors.red:color,
          height:100,
          width:100
          ))
        ));
  }
  
 List<TabModel> list1 =[]; 
 List<TabModel> list2 =[]; 
 
  int listLength=5;
  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
    children: <Widget>[
      column1(),
      column2()
    ],);
  }
}

class TabModel{
   bool isTapped = false;
  TabModel({this.isTapped});
}