Hi, Mariano True, this is a Java question, not an Android question. SO it doesn't r-e-a-l-l-y belong here. But in the interest of speeding you on your way, I will make a couple observations I hope you will find helpful.
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. 2) the NPE occurred during the call to UpdateButtons(), which in turn took place during the call to the above get() method. 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. But now you have a better idea how to narrow this down by yourself, without exposing the code to us, I hope. 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] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
