CODEWITHSUNDEEP
androidbackgroundglobal-variablesresume
Anders
Anders

Reputation: 109

Could the values on global variables have been reset when an Android app resumes?

When an app have been put into the background and later resumes to an activity, is it possible that static class variables set in another Activity could have been reset by the garbage collector and have got the value set to zero?

I use a couple of public static int variables in my main Activity and use them as global variables in various other Activities. I have received a crash report in the developer console from Android Market where the only explanation I can find is that the app resumes to an Activity which uses the value of a public static int variable in another class, but the value has (mysteriously?) become zero. I know that it was set to something else when the app first started. Is this at all possible?

If my suspicion is correct, what is the recommended way to preserve the values of the global variables when an app is put in to background? Save them in SharedPreferences in OnPause() or use onSaveInstanceState or something else?

Upvotes: 2

Views: 3045

Answers (3)

Namor Alves
Namor Alves

Reputation: 143

You can save this values on SQLite on method onDestroy in activity or another method with response to exit.

Upvotes: 0

Stefan
Stefan

Reputation: 4705

Be careful with static variables. Follow the link for an explanation concerning Singleton (which also use a static variable to maintain state): https://stackoverflow.com/a/9004638/1127492

Upvotes: 1

CommonsWare
CommonsWare

Reputation: 1006869

When an app have been put into the background and later resumes to an activity, is it possible that static class variables set in another Activity could have been reset by the garbage collector and have got the value set to zero?

It would not be "reset by the garbage collector". However, the process may have been terminated by Android, to free up memory for other applications.

what is the recommended way to preserve the values of the global variables when an app is put in to background?

Static data members should only be a cache. Data you want to retain regardless of what happens (e.g., process being terminated) needs to go in some persistent store, such as a flat file, SharedPreferences, or database. onPause() is a likely time to arrange to persist that data, as any time after that, your process could be terminated without notice.

Upvotes: 4

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