Code for live updating listView

interests.dart

import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';

class Interests extends StatefulWidget {
  @override
  _InterestsState createState() => _InterestsState();
}

class _InterestsState extends State<Interests> {
  List<String> interests = new List();
  TextEditingController _textController = TextEditingController();

  String newInterest;

  listInterests(newInterest) {
    setState(() {
      print('Interest before = $interests');
      interests.add(newInterest);
      print('Interest after = $interests');
    });
  }

  Widget interestListViewWid() {
    if (interests.isEmpty || interests.length == null) {
      return Container();
    } else {
      return Container(
        // height: 0,
        child: ListView.builder(
          itemCount: interests.length,
          itemBuilder: (BuildContext context, int index) {
            return listItem(newInterest);
          },
        ),
      );
    }
  }

  Widget listItem(newInterest) {
    return Container(
      alignment: Alignment.center,
      decoration: BoxDecoration(
        color: Colors.black,
        borderRadius: BorderRadius.circular(50),
      ),
      child: Row(
        children: <Widget>[
          Text(
            '#',
            style: GoogleFonts.redHatText(
              fontSize: 22,
              color: Colors.pink[500],
            ),
          ),
          Text(newInterest,
              style: GoogleFonts.redHatText(
                fontSize: 22,
                color: Colors.white,
              )),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    double height = MediaQuery.of(context).size.height;
    return Scaffold(
        resizeToAvoidBottomInset: false,
        backgroundColor: Colors.black,
        body: Container(
          height: 700,
          decoration: BoxDecoration(
              image: DecorationImage(
                  image: AssetImage('assets/interests.png'),
                  fit: BoxFit.cover,
                  colorFilter:
                      ColorFilter.mode(Colors.black54, BlendMode.luminosity))),
            child: Column(
              children: <Widget>[
                Container(
                    alignment: Alignment.center,
                    margin: EdgeInsets.only(top: 50, left: 20, right: 20),
                    child: Material(
                      shape: RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(50)),
                      elevation: 20,
                      shadowColor: Colors.grey[400],
                      child: TextField(
                        maxLines: 1,
                        style: GoogleFonts.redHatText(
                            fontSize: 22, fontWeight: FontWeight.w600),
                        keyboardType: TextInputType.text,
                        autocorrect: true,
                        controller: _textController,
                        decoration: InputDecoration(
                          // contentPadding: EdgeInsets.all(2),
                          filled: true,
                          fillColor: Colors.white,
                          border: OutlineInputBorder(
                            borderRadius: BorderRadius.circular(50),
                            borderSide: BorderSide.none,
                          ),
                          // focusedBorder: OutlineInputBorder(
                          //   borderRadius: BorderRadius.circular(50),
                          //   borderSide: BorderSide(color: Colors.grey[300]),
                          // ),
                          prefix: Container(
                            padding: EdgeInsets.only(left: 20),
                            child: Text(
                              '#',
                              style: GoogleFonts.redHatText(
                                fontSize: 22,
                                color: Colors.pink[500],
                              ),
                            ),
                          ),
                          suffixIcon: IconButton(
                            padding: EdgeInsets.only(right: 20),
                            onPressed: () {
                              newInterest = "";
                              // String newInterests =
                              newInterest = '#' + _textController.text;
                              print('newInterest  = $newInterest ');
                              listInterests(newInterest);
                            },
                            icon: Icon(
                              Icons.arrow_forward,
                              color: Colors.grey[700],
                              size: 25,
                            ),
                          ),
                          labelStyle: GoogleFonts.redHatText(
                              fontSize: 22, fontWeight: FontWeight.w600),
                        ),
                      ),
                    )),

                //if(interests.isEmpty){ Container()},
                // else{ listItem(newInterests)}
                Expanded(child: interestListViewWid()),
              ],
            ),
          ),
        );
  }
}