flutter - 颤振变量未传入类小部件

Question

如何将声明的变量传递给类小部件。它显示错误“未定义的名称 abcd”。但我已经宣布了。如何在 Text 小部件中传递此变量 abcd。附上代码。提前致谢。

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final String abcd = "abcd";
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: Column(
          children: [
            TextField(),
            OkButton(),
          ],
        ),
      ),
    );
  }
}

class OkButton extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      padding: EdgeInsets.all(4),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.center,
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          FlatButton(
            onPressed: () {},
            child: Text("ok"),
          ),
          Text(abcd),
        ],
      ),
    );
  }
}

标签： flutterclassvariables

Answer 1

在其中添加一个构造函数，该构造函数OkButton接受一个String.

class OkButton extends StatelessWidget {
  OkButton({@required this.text});

  final String text;

  ...
    Text(text), // from Text(abcd),
  ...
}

然后，当您创建 时OkButton，设置text属性。

OkButton(text: abcd),