Solution of getactivity NULL for fragment caused by activity being recycled

These two days have been plagued by this problem, if the app is running in the background for a long time, then click into will crash, and fragment page overlap phenomenon, let me very uncomfortable. Study the day and finally understand the principles and solve them. The solution is as follows:

if the system is out of memory, or switching between the screen, or the app is running in the background for a long time, the activity may be reclaimed by the system, and then fragment will not be recycled as the activity is recycled, resulting in fragment losing the corresponding activity.

Here, suppose we inherit from the Fragmentactivity class as Mainactivity, which uses the fragment as Fragmenta.

The app changes: For some reason system recovery mainactivity--Fragmenta is not recycled--click on the app again--first loaded is the non-recycled fragmenta page -- Because mainactivity is recycled , the system restarts mainactivity andFragmenta is reloaded again-the page is cluttered because a layer of non-recyclable The Fragmenta is covered on top of it-(if Fragmenta uses the Getactivity () method ) It will report a null pointer, and a crash appears.

Although the principle is a bit around, the solution is simple:

mainactivity Rewrite the Onsaveinstancestate method, Super.onsaveinstancestate (outstate), comment out , let it no longer save fragment state, Achieve the effect of being recycled along with mainactivity!

Solution of getactivity NULL for fragment caused by activity being recycled