Disable AlertDialog button on value change of TextFormField Flutter

Copy Paste This Code, Its Working fine, I have used StateFullBuilder Widget for updating the state of the AlertDialogBox.

For More Reference On updating or refreshing the DialogBox Click HERE

Below Is The Code

import 'dart:async';import 'package:flutter/material.dart';class MyTimer extends StatefulWidget {  @override  _MyTimerState createState() => _MyTimerState();}class _MyTimerState extends State<MyTimer> {    bool isValidAlert = false;  bool isValidScafold = false;  _displayDialog(BuildContext context) async {    return showDialog(        context: context,        builder: (context) {          return StatefulBuilder(builder: (context, setState) {            return AlertDialog(              title: Text('TextField AlertDemo'),              content: _containerAlert(setState),              actions: <Widget>[                RaisedButton(                  onPressed: isValidAlert                      ? () {                          print("ISVALID:");                        }                      : null,                  child: Text("Click Me"),                )              ],            );          });        });  }  Widget _container() {    return Container(      margin: EdgeInsets.all(25),      child: Center(        child: Column(          mainAxisAlignment: MainAxisAlignment.center,          children: [            TextFormField(              onChanged: (text) {                setState(() {                  if (text.length > 5) {                    isValidScafold = true;                  } else {                    isValidScafold = false;                  }                });              },              decoration: InputDecoration(labelText: 'Enter Text'),            ),            SizedBox(height: 15),            RaisedButton(              onPressed: isValidScafold                  ? () {                      print("ISVALID:");                    }                  : null,              child: Text("Done!"),            )          ],        ),      ),    );  }  Widget _containerAlert(StateSetter setState) {    return Container(      margin: EdgeInsets.all(25),      child: Center(        child: Column(          mainAxisAlignment: MainAxisAlignment.center,          children: [            TextFormField(              onChanged: (text) {                setState(() {                  if (text.length > 5) {                    isValidAlert = true;                  } else {                    isValidAlert = false;                  }                  print(text);                });              },              decoration: InputDecoration(labelText: 'Enter Text'),            ),            SizedBox(height: 15),            RaisedButton(              onPressed: isValidAlert                  ? () {                      print("ISVALID:");                    }                  : null,              child: Text("Done!"),            )          ],        ),      ),    );  }  @override  Widget build(BuildContext context) {    return Scaffold(      body: Column(        mainAxisAlignment: MainAxisAlignment.center,        children: [          _container(),          RaisedButton(            onPressed: () {              _displayDialog(context);            },            child: Text("Show Alert"),          )        ],      ),    );  }}