设置键盘和验证器

String numberValidator(String value) {
  if(value == null) {
    return null;
  }
  final n = num.tryParse(value);
  if(n == null) {
    return '"$value" is not a valid number';
  }
  return null;
}

new TextFormField(
    keyboardType: TextInputType.number, 
    validator: numberValidator, 
    textAlign: TextAlign.right
    ...

https://docs.flutter.io/flutter/material/TextFormField/TextFormField.html https://docs.flutter.io/flutter/services/TextInputType-class.html

以下是Flutter中实际手机键盘的代码:

     //Mobile
            const TextField(
              keyboardType: TextInputType.number,
              decoration: InputDecoration(
                  prefixIcon: Icon(Icons.phone), hintText: 'Mobile'),
            ),

下面是数字键盘的代码: keyboardType: TextInputType。当你在文本框中添加这个代码时，它将打开数字键盘。

  final _mobileFocus = new FocusNode();
  final _mobile = TextEditingController();


     TextFormField(
          controller: _mobile,
          focusNode: _mobileFocus,
          maxLength: 10,
          keyboardType: TextInputType.phone,
          decoration: new InputDecoration(
            counterText: "",
            counterStyle: TextStyle(fontSize: 0),
            hintText: "Mobile",
            border: InputBorder.none,
            hintStyle: TextStyle(
              color: Colors.black,
                fontSize: 15.0.
            ),
          ),
          style: new TextStyle(
              color: Colors.black,
              fontSize: 15.0,
           ),
          );

设置你的keyboardType为TextInputType.number，

例如:keyboardType: TextInputType.number，

         TextFormField(
            controller: yourcontroller,
            keyboardType: TextInputType.number,
            decoration: const InputDecoration(
              labelText: 'Mobile',
              suffixIcon: Padding(
                padding: EdgeInsets.only(),
                child:
                Icon(Icons.phone_outlined, color: Color(0xffff4876)),
              ),
            ),
            validator: (text) {
              if (text == null || text.isEmpty) {
                return 'Please enter your Mobile No.';
              }
              return null;
            },
          ),

TextField小部件需要设置keyboardType: 和inputFormatters: <TextInputFormatter>[FilteringTextInputFormatter。digitsOnly]只接受数字作为输入。

     TextField(
            keyboardType: TextInputType.number,
            inputFormatters: <TextInputFormatter>[
              FilteringTextInputFormatter.digitsOnly
            ], // Only numbers can be entered
          ),

在DartPad中的例子

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

    void main() => runApp(new MyApp());
    
    class MyApp extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          home: HomePage(),
          theme: ThemeData(primarySwatch: Colors.blue),
        );
      }
    }
    
    class HomePage extends StatefulWidget {
      @override
      State<StatefulWidget> createState() {
        return HomePageState();
      }
    }
    
    class HomePageState extends State<HomePage> {
      @override
      Widget build(BuildContext context) {
        return Scaffold(
          backgroundColor: Colors.white,
          body: Container(
              padding: const EdgeInsets.all(40.0),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Text("This Input accepts Numbers only"),
                  SizedBox(height: 20),
                  TextField(
                    decoration: InputDecoration(
                      focusedBorder: OutlineInputBorder(
                        borderSide:
                            BorderSide(color: Colors.greenAccent, width: 5.0),
                      ),
                      enabledBorder: OutlineInputBorder(
                        borderSide: BorderSide(color: Colors.red, width: 5.0),
                      ),
                      hintText: 'Mobile Number',
                    ),
                    keyboardType: TextInputType.number,
                    inputFormatters: <TextInputFormatter>[
                      FilteringTextInputFormatter.digitsOnly
                    ], // Only numbers can be entered
                  ),
                  SizedBox(height: 20),
                  Text("You can test be Typing"),
                ],
              )),
        );
      }
    }

您可以使用keyboardType参数轻松更改输入类型 你有很多可能性检查文档TextInputType 所以你可以使用号码或电话值

 new TextField(keyboardType: TextInputType.number)