CODEWITHSUNDEEP
androidandroid-fragmentsandroid-activitynullpointerexception
Notbad
Notbad

Reputation: 6306

What to do when activity is destroyed but I must continue executing code in fragment?

I have a pretty odd problem here. In a fragment, I do a process and when the process finishes I show an advert that callsback to the fragment when user clicks/dismisses the ad. The problem is that in some devices when the ad calls back to the handler (that is in the running fragment) the activity containing the fragment has been destroyed, but I need to do some more work through a runnable. So, in this case the runnable throws a NullPointerException int is run method when executed.

I could just check if the activity is still alive and run just the runnable when it is, but in the cases it is not alive I still need to continue to do the part of the job that needs to be done after the ad.

How do you handle this kind of situations? I have been thinking about the problem during some hours without finding a solution to this.

Thanks in advance.

Upvotes: 0

Views: 87

Answers (2)

user7446225
user7446225

Reputation:

mmm the way this is asked I am not sure what you are asking, perhaps some text connectors might work, I am not sure if this is a quite basic question about state changes or a very complex one.

from what I understood:

wouldn't this be the same problem as when you flip screen? make a Bundle of the data that is restored through activity changes. This way if your activity has been Destroyed you restore it

fragments have a feature that you can use to keep instance alive across a configuration change: retainInstance setRetainInstance(true) // false by default

Parcelable like Serializable, is an API for saving an object out to a stream of bytes. Objects may elect to implement the Parcelable interface if they are what we will call "stashable" here. Objects are stashed in Java by putting them in a Bundle, or by marking them Serializable so they can be serialized, or by implementing the Parcelable interface. Whichever way you do it, the same idea applies: you should not be using any of these tools unless your object is stashable ---or---

turn that "advert" of yours into an Alert, which wont mess with the Activity.

---or---

run the response on a different thread?

Upvotes: 0

Gagan
Gagan

Reputation: 755

You can use AsyncTask in this case .

AsyncTask processes are not automatically killed by the OS. AsyncTask processes run in the background and is responsible for finishing it's own job in any case. You can cancel your AsycnTask by calling cancel(true) method. This will cause subsequent calls to isCancelled() to return true. After invoking this method, onCancelled(Object) method is called instead of onPostExecute() after doInBackground() returns.

Hope it helps..

Upvotes: 1

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