Showing a button to the user based on the data entered in the TextFormField

final TextEditingController _weight = TextEditingController();

 if (_weight.text.contains(RegExp(r'[0-9]')))
        Padding(
            padding: const EdgeInsets.only(bottom: 20),
            child: BMIButton(
              onpressed: () {
                Navigator.push(
                  context,
                  PageTransition(
                      type: PageTransitionType.rightToLeft,
                      child: BMIHeight(),
                      inheritTheme: true,
                      ctx: context),
                );
              },
            ))

I’m trying to show an OutlinedButton when the user enters some data into the textFormField. When I enter a value in the TextFormField and confirm, it doesn’t show a button, but when I hot reload it, it sees that value and shows the button.

>Solution :

Try to add listener and call setState to update ui

 late final TextEditingController _weight = TextEditingController()
    ..addListener(() {
      setState(() {});
    });

And override the dispose method and depose this controller.