ERROR: null root node returned by UiTestAutomationBridge

Hi i am using Android p device in which some times (adb shell uiautomator dump) command throws "ERROR: null root node returned by UiTestAutomationBridge" error. Is there any alternate way to fetch UIHierarchy. Even i tried with Appium but we have to install prerequisite app to test with appium. Please give some alternation solution. Thanks in advance.

_Originally posted by @IndhumathiElumalai in https://github.com/googlesamples/android-testing/issues/193#issuecomment-507549380_

首先在 Android P 设备上复现 `adb shell uiautomator dump`，并记录它何时返回“null root node returned by UiTestAutomationBridge”。将结果与 issue 中提到的 Appium 方法进行比较。完成这项工作需要确定并记录一种不使用所述前置应用来获取 UI 层次结构的可行替代方式，但该 issue 没有提供具体的验收标准。

由索引模型根据 Issue 内容生成。