How to replace multiple text in flutter?

I am not good in RegExp, so maybe there is some better way of doing it.

String _textSelect(String str) {
  str = str.replaceAll('e', 'é');
  str = str.replaceAll('i', 'I');
  str = str.replaceAll('b', '*');
  str = str.replaceAll('v', '<');
  return str;
}


String output = _textSelect('English is blowing vhistle?'); 

Edit:

final myController = TextEditingController();
String str = '';

String _textSelect(String str) {
  str = str.replaceAll('e', 'é');
  str = str.replaceAll('i', 'I');
  str = str.replaceAll('b', '*');
  str = str.replaceAll('v', '<');
  return str;
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text('Retrieve Text Input'),
    ),
    body: Padding(
      padding: const EdgeInsets.all(16.0),
      child: TextField(
        controller: myController,
      ),
    ),
    floatingActionButton: FloatingActionButton(
      // When the user presses the button, show an alert dialog containing
      // the text that the user has entered into the text field.
      onPressed: () {
        str = _textSelect(myController.text); //update
        return showDialog(
          context: context,
          builder: (context) {
            return AlertDialog(
              // Retrieve the text the that user has entered by using the
              // TextEditingController.
              content: Text(
                str,
                style: TextStyle(fontSize: 50, fontFamily: 'Italy'),
              ),
            );
          },
        );
      },
      tooltip: 'Show me the value!',
      child: Icon(Icons.text_fields),
    ),
  );
}

Your code seems to be fine as far as I can tell, only thing you haven't done is to change the state of str variable;

So do this:

onPressed: () {
             setState(() { _textSelect();}); //add setState here. 

              return showDialog(
                context: context,
                builder: (context) {
                  return AlertDialog(

                    content: Text(
                    str,
                    style:TextStyle(
                      fontSize:50,
                      fontFamily:"Italy"),),
                  );
                },
              );