If the app is killed, the  next time the user returns to it only the visible
activities at that point will be re-started; not the entire activity stack.

On Fri, Aug 6, 2010 at 4:48 AM, Michael A. <[email protected]> wrote:

> I am seeing a lot of NullPointerException in my code at the moment
> from public static variables.
>
> I use these variables to store, e.g., my image library (used in
> Activities throughout my code). All of them are initialized in the
> OnCreate of my apps Base activity, and I check that they are
> initialized in OnResume just to be certain (and initialize them if
> they have somehow become nulled).
>
> // Main APP Activity
> MainActivity {
> public static GlobalObject lib;
>
> void OnCreate() {
>  if (lib == null)
>    lib = new GlobalObject();
> }
>
> void OnResume() {
>  if (lib == null)
>    lib = new GlobalObject();
> }
>
> }
>
> // Some other activity instantiated later
> OtherActivity {
> void onCreate() {
>  lib.doSomething();  // This line will sometimes fail with a
> NullPointerException
> }
>
> }
>
> I am quite unable to recreate the situation in which this
> NullPointerException occurs. As I understand the activity lifecycle,
> it should not be possible for lib to be null when OtherActivity is
> created (if OtherActivity is in memory, MainActivity's static
> variables should also be in memory and if the app is killed, it should
> start over from MainActivity?), but that is the error I seem to be
> getting.
>
> Suggestions, anyone? I suppose I am probably overlooking something
> simple, but I just can't see it.
>
> Regards,
>
> Michael A.
>
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-- 
Dianne Hackborn
Android framework engineer
[email protected]

Note: please don't send private questions to me, as I don't have time to
provide private support, and so won't reply to such e-mails.  All such
questions should be posted on public forums, where I and others can see and
answer them.

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