如何改变按钮文本取决于文本域?

Question

输入图片描述

在这里我想改变的按钮，这取决于一个文本字段，喜欢当文本字段被填充，然后显示按钮C，当点击C按钮，然后改变按钮名称C到AC，还需要改变文本字段填充为空。

Answer 1

检查这个示例，以演示您需要的输出

import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Location',
theme: ThemeData(
primarySwatch: Colors.amber,
),
home: const MyHomePage(title: 'Flutter Location Demo'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key, this.title}) : super(key: key);
final String? title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final TextEditingController _controller = TextEditingController();
String? buttonText;
@override
void initState() {
_controller.addListener(_checkTextIsEmpty);
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title!),
),
body: Center(
child: Column(
children: [
TextField(
controller: _controller,
onChanged: (value) {},
),
Text(buttonText ?? ''),
],
),
),
);
}
void _checkTextIsEmpty() {
final value = _controller.text.isEmpty ? "AC" : "C";
setState(() {
buttonText = value;
});
}
}