Create an Empty List as FilteredSearch= [];

​

Existing List as List<String> animals=['cat','dog','rat'];

Inside Textfield OnChanged property :

onChanged:(query){

      filtersearch();

      };

      create an function for filtering the search:

      void filtersearch(){

      setState((){

           FilteredSearch = animals.where((e)=>e.toLowerCase().contains(query.toLowerCase())).toList();

           });

           }

           Then In Initstate:

           void initState(){

           super.initState();

           FilteredSearch = animals;

           }

           In ListView:

           use itemCount:FilteredSearch.length,

           for Access text : FilteredSearch[index]..