- 提示：Hardcoded string "用户名", should use @string resource
解决：https://blog.csdn.net/zhandoushi1982/article/details/8675756
2.页面布局不见了
解决：https://blog.csdn.net/zhandoushi1982/article/details/8675756
3.Failed to load AppCompat ActionBar with unknown error.
解决：<style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar"></style>
4.PACKAGE_USAGE_STATS权限报错 permissions is only granted to system apps
解决：androidstudio中: 依次选择 File - Setting - Editor - Inspections, 然后在打开的页面中选择 Android > Lint > Correctness 下的 Using system app permission , 然后设置右侧的 Severity 为 Warning
