chat_list_on_tap.dart

import 'package:flutter/material.dart';

class ChatList extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ListView.builder(itemBuilder: (context, index) {
      return ListTile(
        title: Text('Contact $index'),
        //// onTap START ////
        onTap: () {
           Navigator.push(context, MaterialPageRoute(builder: (context) {
            return ChatRoom(_chatItems[index]); // passing data to chat room
          }));
        },
        //// onTap END ////
      );
    });
  }
}