flutter - Flutter/Dart-获取要在Text Widget中使用的PageView.Builder的索引号？

Question

我在PageView.builder中有一个StatelessWidget。我需要获取当前查看页面的当前索引号，以显示在我的版本的文本小部件中。
希望我可以在文本小部件中简单地使用currentIndex.toString()作为变量，但是Android Studio用红色下划线标出并警告我undefined name currentIndex。如何获得正确的变量？

 class StageBuilder extends StatelessWidget {
  final List<SpeakContent> speakcrafts;
  StageBuilder(this.speakcrafts);

  final PageController controller = PageController(initialPage: 0);

  @override
  Widget build(context) {
    return PageView.builder(
      controller: controller,
      itemCount: speakcrafts.length,
      itemBuilder: (context, int currentIndex) {
        return createViewItem(speakcrafts[currentIndex], context);
      },
    );
  }

  Widget createViewItem(SpeakContent speakcraft, BuildContext context) {
  
    return Container(
        child: Text(currentIndex.toString()),
     )     
  }
}

Answer 1

您需要将currentIndex传递到createViewItem中

 class StageBuilder extends StatelessWidget {
  final List<SpeakContent> speakcrafts;
  StageBuilder(this.speakcrafts);

  final PageController controller = PageController(initialPage: 0);

  @override
  Widget build(context) {
    return PageView.builder(
      controller: controller,
      itemCount: speakcrafts.length,
      itemBuilder: (context, int currentIndex) {
        return createViewItem(speakcrafts[currentIndex], context, currentIndex);
      },
    );
  }

  Widget createViewItem(SpeakContent speakcraft, BuildContext context, int currentIndex) {
  
    return Container(
        child: Text(currentIndex.toString()),
     );
  }
}