Ok, meanwhile a coworker of mine pointed out that this is a known issue with autoboxing (not showing up in the stacktrace), it was just unknown to me.
http://javahowto.blogspot.com/2006/07/not-your-typical-npe.html Thanks for your help guys. On Wed, Jun 23, 2010 at 8:39 AM, Mariano Kamp <[email protected]>wrote: > On Wed, Jun 23, 2010 at 1:23 AM, Indicator Veritatis <[email protected]>wrote: > >> True, this is a Java question, not an Android question. SO it doesn't >> r-e-a-l-l-y belong here. > > I am glad we cleared that up. > > >> 1) no, the NPE does not imply that isMarkAllReadPossibleCache is the >> null variable. Rather, it implies that in the course of trying to >> execute the get method of isMarkAllReadPossibleCache, the DVM >> encountered a null pointer. >> > How so? Where do you see the get() method? > > >> 2) the NPE occurred during the call to UpdateButtons(), which in turn >> took place during the call to the above get() method. >> > I am really puzzled by that. > You mean that looking at the stacktrace the NPE happens here: > > com.newsrob.activities.AbstractNewsRobListActivity.updateButtons(AbstractNewsRobListActivity.java:236) > ? > How do you come to this conclusion? In case of a non-wrapped exception > isn't the top stack frame the place where the exception occurs? An exception > blows up and the JVM provides the stacktrace up to this point. You think > otherwise? > > 3) to tell in any more detail where it came from, I would need the >> rest of your stack trace, which you chose not to show. > > The stack trace is complete. > > >> But now you >> have a better idea how to narrow this down by yourself, without >> exposing the code to us, I hope. > > I don't have a better idea and now you got me confused about how to read > the stack trace. > > As this is kind of a last straw I would be delighted to learn something new > about exceptions. Maybe that's the cue that's missing. > > >> On Jun 22, 2:59 am, Mariano Kamp <[email protected]> wrote: >> > Hey guys. >> > >> > This is not an Android issue per-se, but I am puzzled about a Java issue >> and >> > want to pick your brains. >> > >> > I recently got a couple of bug reports with a NPE that I don't >> understand >> > and can't reproduce myself. Here is an abbreviated representation of the >> > offending class. I tried to stay as close to the actual code as >> possible. >> > >> > public class EntryManager { >> > >> > private static EntryManager instance; >> > private Map<DBQuery, Boolean> isMarkAllReadPossibleCache; >> > >> > private EntryManager(Context ctx) { >> > .. >> > isMarkAllReadPossibleCache = new HashMap<DBQuery, Boolean>(); >> > .. >> > } >> > >> > public static synchronized EntryManager getInstance(final Context >> context) >> > { >> > if (instance == null) >> > instance = new EntryManager(context.getApplicationContext()); >> > return instance; >> > } >> > >> > void fireModelUpdated(final String atomId) { >> > .. >> > isMarkAllReadPossibleCache.clear(); >> > .. >> > } >> > >> > public boolean isMarkAllReadPossible(final DBQuery dbq) { >> > if (!isMarkAllReadPossibleCache.containsKey(dbq)) >> > isMarkAllReadPossibleCache.put(dbq, >> > databaseHelper.isMarkAllReadPossible(dbq)); >> > >> > return isMarkAllReadPossibleCache.get(dbq); <!-- NPE is raised >> here >> > } >> > .. >> > >> > } >> > >> > In the last line from above a NPE is thrown. So the instance variable >> > isMarkAllReadPossibleCache must be null, right? But I don't see where >> this >> > could happen. It's initialized in the constructor and never set to null >> > afterwards. >> > >> > For completeness here is a stack trace: >> > >> > java.lang.NullPointerException >> > at >> com.newsrob.EntryManager.isMarkAllReadPossible(EntryManager.java:1529) >> > at >> > >> com.newsrob.activities.AbstractNewsRobListActivity.shouldMarkAllReadButtonBeEnabled(AbstractNewsRobListActivity.java:327) >> > at >> > >> com.newsrob.activities.AbstractNewsRobListActivity.updateButtons(AbstractNewsRobListActivity.java:236) >> > at >> > >> com.newsrob.activities.AbstractNewsRobListActivity.access$2(AbstractNewsRobListActivity.java:215) >> > <-- removed the private access modifier meanwhile >> > at >> > >> com.newsrob.activities.AbstractNewsRobListActivity$13.run(AbstractNewsRobListActivity.java:626) >> > at android.os.Handler.handleCallback(Handler.java:587) >> > at android.os.Handler.dispatchMessage(Handler.java:92) >> > at android.os.Looper.loop(Looper.java:123) >> > at android.app.ActivityThread.main(ActivityThread.java:4203) >> > at java.lang.reflect.Method.invokeNative(Native Method) >> > at java.lang.reflect.Method.invoke(Method.java:521) >> > at >> > >> com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) >> > at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549) >> > at dalvik.system.NativeStart.main(Native Method) >> > >> > Any ideas? >> > >> > Cheers, >> > Mariano >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Android Developers" group. >> To post to this group, send email to [email protected] >> To unsubscribe from this group, send email to >> [email protected]<android-developers%[email protected]> >> For more options, visit this group at >> http://groups.google.com/group/android-developers?hl=en >> > > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. 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