为什么有时小吃店会失败

Question

请帮助解释为什么有时我的 SnackBar 显示错误。我不明白在什么情况下会出现这个问题。我还想指出，即使它显示错误，但在应用程序本身中，它工作正常。

这是我的代码：

void showFailedSnackBar(String s) {
    SnackBar snackBar = SnackBar(
      content: Text(s),
      duration: Duration(seconds: 3),
      backgroundColor: Theme.of(context).primaryColor,
    );

    ScaffoldMessenger.of(context).showSnackBar(snackBar);
  }

这是错误：

E/flutter ( 7879): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: This widget has been unmounted, so the State no longer has a context (and should be considered defunct).
E/flutter ( 7879): Consider canceling any active work during "dispose" or using the "mounted" getter to determine if the State is still active.

Answer 1

尝试检查小部件是否仍然安装在三个中：

void showFailedSnackBar(String s) {
    if (mounted) {
    SnackBar snackBar = SnackBar(
      content: Text(s),
      duration: Duration(seconds: 3),
      backgroundColor: Theme.of(context).primaryColor,
    );

    ScaffoldMessenger.of(context).showSnackBar(snackBar);
    }

  }