android - 为什么使用 Fragment#setRetainInstance(boolean)？

Question

我发现 Fragment#setRetainInstance(true) 令人困惑。这是从 Android Developer API 中提取的 Javadoc :

public void setRetainInstance (boolean retain)

Control whether a fragment instance is retained across Activity re-creation (such as from a configuration change). This can only be used with fragments not in the back stack. If set, the fragment lifecycle will be slightly different when an activity is recreated:

• onDestroy() will not be called (but onDetach() still will be, because the fragment is being detached from its current activity).
• onCreate(Bundle) will not be called since the fragment is not being re-created.
• onAttach(Activity) and onActivityCreated(Bundle) will still be called.

问题:作为开发人员，您如何使用它，为什么它会让事情变得更容易？

Answer 1

How do you as a developer use this

调用setRetainInstance(true)。我通常在 onCreateView() 或 onActivityCreated() 中使用它。

and why does it make things easier?

它往往比 onRetainNonConfigurationInstance() 更简单地处理跨配置更改的数据保留(例如，将设备从纵向旋转到横向)。未保留的 fragment 在配置更改时被销毁并重新创建；保留的 fragment 不是。因此，这些保留 fragment 持有的任何数据都可用于配置更改后的 Activity 。