Flutter - 当文本字段具有焦点时隐藏提示文本

Question

我需要知道当我关注文本字段时如何隐藏提示文本。这是我的代码:

class _ContactoState extends State<Contacto> {
  FocusNode focusMsj;

  @override
  void initState() {
    super.initState();

    focusMsj = FocusNode();
    focusMsj.addListener(() {
      if (!focusMsj.hasFocus) {
        FocusScope.of(context).requestFocus(focusMsj);
      }
    });
  }

TextField(
          focusNode: focusMsj,
            hintText: focusMsj.hasFocus ? ' ' : 'Hint Text',)

return WillPopScope(
          child: Listener(
            onPointerUp: (e) {
              focusMsj.hasFocus ? FocusScope.of(context).requestFocus(FocusNode()): '';
            },

谢谢

Answer 1

为了做到这一点，你需要做类似的事情

class Play extends StatefulWidget {
  @override
  _PlayState createState() => _PlayState();
}

class _PlayState extends State<Play> {
  FocusNode focusNode = FocusNode();
  String hintText = 'Hello , iam Hint';
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    focusNode.addListener(() {
      if (focusNode.hasFocus) {
        hintText = '';
      } else {
        hintText = 'Hello , iam Hint';
      }
      setState(() {});
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(onPressed: () {
        print(focusNode.hasFocus);
      }),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            TextField(
              focusNode: focusNode,
              decoration: InputDecoration(
                hintText: hintText,
              ),
            ),
            TextField(
              decoration: InputDecoration(
                hintText: '!!',
              ),
            ),
          ],
        ),
      ),
    );
  }
}

很快我就通过它的 focusNode 属性收听了 TextField 。当 TextField 具有焦点时，我使hintText属性等于空字符串值