Empty value in TextFormField

Question

This is an AlertDialog, when the person types the name, the name cannot be null or empty.

import 'package:flutter/material.dart';

abstract class ComponentDialog {
  static final TextEditingController _controller = TextEditingController();

  static Future<dynamic> BuidDialog(
      BuildContext context,
      String titleLabel,
      String inputLabel,
      String cancelLabel,
      String confirmLabel,
      ) =>

      showDialog(
        context: context,
        builder: (BuildContext context) => AlertDialog(
          title: Text(titleLabel),
          content: TextFormField(
            controller: _controller,
            decoration: InputDecoration(
              labelText: inputLabel,
              border: const OutlineInputBorder(
                borderSide: BorderSide(
                  color: Colors.pinkAccent, // TODO: charge color
                ),
              ),
            ),
          ),
          actions: <Widget>[
            TextButton(
              onPressed: () => Navigator.pop(context),
              child: Text(cancelLabel),
            ),
            TextButton(
              onPressed: () {
                if (stringTitleLabel.IsNullOrWhiteSpace(objeto)) {

                  return;
                }
                Navigator.pop(context, _controller.text);
              },
              child: Text(confirmLabel),
            ),
          ],
        ),
      );
}

Answer 1

 Padding(
       padding: EdgeInsets.only(left: 2.0, top: 1.0, right: 120.0, bottom: 4.0),
       child: Text(
                'name', //username
                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 16,),
                ),
       ),