getTimeZone() causes NPE

[rfc2822]

ical4j 2.2.20, Android

When calling getTimeZone() on a registry created by TimeZoneRegistryFactory.getInstance().createRegistry(), it sometimes generates a NullPointerException:

java.lang.NullPointerException: Attempt to invoke virtual method 'void java.util.Calendar.setTimeZone(java.util.TimeZone)' on a null object reference
      at java.text.DateFormat.setTimeZone(DateFormat.java:690)
      at net.fortuna.ical4j.model.Iso8601.<init>(Iso8601.java:77)
      at net.fortuna.ical4j.model.Date.<init>(Date.java:150)
      at net.fortuna.ical4j.model.DateTime.<init>(DateTime.java:262)
      at net.fortuna.ical4j.util.Dates.getInstance(Dates.java:223)
      at net.fortuna.ical4j.model.component.Observance.getLatestOnset(Observance.java:230)
      at net.fortuna.ical4j.model.TimeZone.getRawOffset(TimeZone.java:180)
      at net.fortuna.ical4j.model.TimeZone.<init>(TimeZone.java:69)
      at net.fortuna.ical4j.data.CalendarBuilder$ContentHandlerImpl.endComponent(CalendarBuilder.java:245)
      at net.fortuna.ical4j.data.CalendarParserImpl$ComponentParser.parse(CalendarParserImpl.java:444)
      at net.fortuna.ical4j.data.CalendarParserImpl$ComponentParser.access$900(CalendarParserImpl.java:406)
      at net.fortuna.ical4j.data.CalendarParserImpl$PropertyListParser.parse(CalendarParserImpl.java:208)
      at net.fortuna.ical4j.data.CalendarParserImpl.parseCalendar(CalendarParserImpl.java:115)
      at net.fortuna.ical4j.data.CalendarParserImpl.parseCalendarList(CalendarParserImpl.java:180)
      at net.fortuna.ical4j.data.CalendarParserImpl.parse(CalendarParserImpl.java:149)
      at net.fortuna.ical4j.data.CalendarBuilder.build(CalendarBuilder.java:198)
      at net.fortuna.ical4j.data.CalendarBuilder.build(CalendarBuilder.java:178)
      at net.fortuna.ical4j.data.CalendarBuilder.build(CalendarBuilder.java:165)
      at net.fortuna.ical4j.model.TimeZoneLoader.loadVTimeZone(TimeZoneLoader.java:99)
      at net.fortuna.ical4j.model.TimeZoneRegistryImpl.getTimeZone(TimeZoneRegistryImpl.java:181)
      at at.bitfire.ical4android.AndroidEvent.populateEvent(AndroidEvent.kt:169)

I don't know which time zone causes the problems yet, but I think getTimeZone() should not throw an unchecked exception in any case.

[rfc2822]

Same as #219

[rfc2822]

I have opened it again because the other issue is about returning null, and this is about a NullPointerException. Unfortunately, I couldn't find the cause yet although this seems to occur quite often.

[noloman]

Same thing happening here, with 2.0.0. What's the status of this? Any ideas? workarounds?

[rfc2822]

@noloman Does it happen in Android 8.0.0 only or on other platforms? Meanwhile I assume this is some kind of firmware bug, especially because the NPE happens in java.text.DateFormat.setTimeZone(DateFormat.java:690) and not in ical4j

[noloman]

@rfc2822 it only happens (for now on Android 8.0.0) but it only happens when using the library for parsing a DateTime. Is there any known workaround, even if it's modifying the backend? Thanks for the good work guys!

[noloman]

BTW this is also happening on other versions of Android, not only 8. Could it maybe not be an Android bug?

[rfc2822]

@noloman On which other version have you seen that? We have only seen it with Android 8.0, although we have many users with various versions.

Uninstalling the app and installing it again sometime fixes the problem magically, which is very strange…

For reference, this is our thread: https://forums.bitfire.at/post/9654

[noloman]

well unfortunately, telling our customers to remove and install the app is really not a suitable solution, as you will understand.
Unfortunately I haven't ever been able to reproduce this issue, neither with the emulator nor with a real device, so I'm out of ideas

[rfc2822]

@noloman Same here (not reproducible). At the moment, I think it may be somehow related to an Android cache…

And we tell our customers to re-install, too… just because there's no better solution at the moment. This is why I have mentioned it.

[benfortuna]

If you have suggestions on how to work around the issue let me know (eg extra error handling)

[noloman]

well I can give you guys several datetime strings in the ICS that can't be parsed (20180714T193000 for example). If you try to debug with that String -I haven't personally tried THAT string, but I have tried with others- you can dive into the debug until you reach the NPE

[noloman]

Hi, BTW in which versions, if any, can you guys NOT reproduce this? I was using 2.2.0 and I have upgraded now to 3.0.1, so hopefully this crash won't happen again?

[rfc2822]

Unfortunately, upgrading to 3.x is not an option for me, because we have to support Android <7, too (and ical4j 3.x requires JDK 8 libraries, which are only available on Android 7+).

[noloman]

What do you mean? I have upgraded and built gradle plus executed the app in an emulator (Oreo) but I didn't have any issue. Is it supposed to crash if it's run in < Oreo? Op di 4 sep. 2018 17:38 schreef rfc2822 <notifications@github.com>:

…

Unfortunately, upgrading to 3.x is not an option for me, because we have to support Android <7, too (and ical4j 3.x requires JDK 8 libraries, which are only available on Android 7+). — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#229 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AALL4GQ2Kys9tEOoldubUbSk4qBQmeo8ks5uXp6OgaJpZM4TZtST> .

[rfc2822]

What do you mean? I have upgraded and built gradle plus executed the app in an emulator (Oreo) but I didn't have any issue. Is it supposed to crash if it's run in < Oreo?

Yes, or does it work for you in <Oreo emulator? There are many operations which rely on the Java 8 API, which requires Android >= 7. Java 8 bytecode wouldn't be the problem, but the API…

[noloman]

Indeed @rfc2822 I understood it completely wrong: it is crashing on devices with Android < Nougat, but working on the newer versions

[rfc2822]

Theoretically, it should be possible to make a class loader which dynamically injects the required classes for Android < 7…