how to show up number firstly and able to change put text too?

Currenly what I did is

keyboardType: TextInputType.number

This makes the first step work well.

However, it cannot be changed back to letters, only numbers are compulsory.

CodePudding user response：

keyboardType: TextInputType.number means your textField is number only.
You can track this with onChange method that do something to change keyboardType to text.

var myKeyboardType = TextInputType.number;

// your textFiled:
TextFiled(
  keyboardType: myKeyboardType,
  inputFormatters: [
    FilteringTextInputFormatter.allow(RegExp("Your rule")),
  ],
  onChanged: (text){
     if(text.length == 1) {// or other way 
         setState((){
           myKeyboardType = TextInputType.text;
           // may need to request focus again.
         }
     }
     else if (text.isEmpty) { //when user delete the number, change keyboard back.
       setState((){
           myKeyboardType = TextInputType.number;
           // may need to request focus again.
         }
     }
  },
),

You can use inputFormatters to limit user's input with regexp.

CodePudding user response：

  Padding(
            padding: const EdgeInsets.all(8.0),
            child: TextField(
         
              focusNode: widget._childnod,
              onChanged: (s) {
                if (s.length == 1) {
                  setState(() {
                    FocusScope.of(context).unfocus();
                    widget._inputType = TextInputType.text;
                 
                  });
               
                  Future.delayed(const Duration(milliseconds: 1), () {
                    FocusScope.of(context).requestFocus(widget._childnod);
                  });
                }
              },
              keyboardType: widget._inputType,
            ),
          )

Here we added future. delayed Because we need a small time gap to reopen the keyboard other wise it wouldn't work.Here we don't use any button instead we use a delay

  Future.delayed(const Duration(milliseconds: 1), () {
                    FocusScope.of(context).requestFocus(widget._childnod);
                  });

May like this:

Sample Code

void main() => runApp(
    MaterialApp(home: Scaffold(appBar: AppBar(), body: Changekeyboard())));

class Changekeyboard extends StatefulWidget {
  Changekeyboard({Key? key}) : super(key: key);
  TextInputType _inputType = TextInputType.number;
  FocusNode? _childnod = FocusNode();

  @override
  _ChangekeyboardState createState() => _ChangekeyboardState();
}

class _ChangekeyboardState extends State<Changekeyboard> {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        children: [
          FlatButton(
              color: Colors.blue,
              onPressed: () {
                FocusScope.of(context).unfocus();
                setState(() {
                  if (widget._inputType == TextInputType.number)
                    widget._inputType = TextInputType.text;
                  else
                    widget._inputType = TextInputType.number;
                });
              },
              child: Text(
                "Change type",
                style: TextStyle(color: Colors.white),
              )),

          Padding(
            padding: const EdgeInsets.all(8.0),
            child: TextField(

              focusNode: widget._childnod,
              onChanged: (s) {
                if (s.length == 1) {
                  setState(() {
                    FocusScope.of(context).unfocus();
                    widget._inputType = TextInputType.text;

                  });

                  Future.delayed(const Duration(milliseconds: 1), () {
                    FocusScope.of(context).requestFocus(widget._childnod);
                  });
                }
              },
              keyboardType: widget._inputType,
            ),
          ),
        ],
      ),
    );
  }
}