如何在Flutter中隐藏某个数字字符后面的字母？

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    String input = '123abc456def';
    String output = hideLettersAfterNumber(input);

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Hide Letters After Number'),
        ),
        body: Center(
          child: Text(output),
        ),
      ),
    );
  }

  String hideLettersAfterNumber(String input) {
    RegExp regExp = RegExp(r'\d+');
    Iterable<Match> matches = regExp.allMatches(input);

    if (matches.isEmpty) {
      return input;
    }

    Match match = matches.first;
    int end = match.end;

    String output = input.substring(0, end);
    output += '*' * (input.length - end);

    return output;
  }
}