小结

在使用Android导览(Android Navigation component)碰到很多问题。解决了一些问题，但是“Skipped xxx frames! The application may be doing too much work on its main thread”这样的的问题一直没有解决。

有关Android导览(Android Navigation component)

参考Android Developer: Migrate to the Navigation component: Migrate to the Navigation component 和
Android Developer: Get started with the Navigation component，可以创建navigation graph方便地对Fragment进行管理。

碰到的问题

• NavController cannot find an ID
  Caused by: java.lang.IllegalArgumentException: ID does not reference a View inside this Activity

• java.lang.IllegalArgumentException: ID未引用此活动中的视图

• xxx does not have a NavController set on xxx

对于碰到的以上的问题，都差不多，是获取Controller时的出现的问题，参考Android开发 报错: xxx does not have a NavController set on xxx，以下代码可以解决：

    @Overrideprotected void onStart() {super.onStart();mController = Navigation.findNavController(MainActivity.this, R.id.nav_host_fragment);}

或者：

    public void navigate(@IdRes int resId, @Nullable Bundle args) {try {navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.nav_host_fragment);mController = navHostFragment.getNavController();mController.navigate(resId, args);} catch (IllegalStateException | IllegalArgumentException ex) {Log.e(TAG_NAV, String.format("Unable to navigate to destination. %s", ex.getMessage()));}}

对于以下碰到的问题始终没有解决：

• Skipped xxx frames! The application may be doing too much work on its main thread

一种说法是创建多线程或者异步任务可以解决，但是试了一下好像不行。

另一种说法是Android应用运行时图片资源过大加载导致处理不过来。

• mdpi = 1x
• hdpi = 1.5x
• xhdpi = 2x
• xxhdpi = 3x
• xxxhdpi = 4x

其中drawable-nodpi是不会进行缩放的，结果试了这种办法也是不行。
创建一个新的分辨率的资源如下：
yourprojectname->app->src->main->res-> New->Image Asset-> select your resolution image required

参考

Android Developer: Migrate to the Navigation component: Migrate to the Navigation component
Android Developer: Get started with the Navigation component
Stackoverflow: Why does my NavController cannot find an ID that I already have?
找不到.findNavController()的正确上下文
Android开发 报错: xxx does not have a NavController set on xxx
Stackoverflow: The application may be doing too much work on its main thread
13、主线程任务太多导致异常退出（The application may be doing too much work on its main thread）
Stackoverflow: Will a density qualified drawable folder or drawable-nodpi take precedence?