NPE in Cache getTableName

[tomrozb]

I'm looking into the crash reports for my app and I'm seeing a few crashes on the same line in ActiveAndroid.

Caused by: java.lang.NullPointerException
       at com.activeandroid.Cache.getTableName(ProGuard:156)
       at com.activeandroid.query.From.addFrom(ProGuard:169)
       at com.activeandroid.query.From.toSql(ProGuard:250)
       at com.activeandroid.query.From.executeSingle(ProGuard:311)

I've searched through the issues and it looks like it's common issue. I see it here: #291 #264 #109

One of my Activities can be started by 3rd party apps and one of the apps starts this activity within its own task. It's started from another process, but my activity is part of the 3rd party app backstack. Even though a new process is created for my app it sometimes crash on getTableName in Cache. The ActiveAndroid initialization code is places inside the onCreate method of the Application class.

Any clues what can be wrong? In my opinion looks like problems with static references in ActiveAndroid or the returned TableInfo is null. What about starting the exported activity from another process, could this be the problem (I don't think so, since a new process is created)?

[daentech]

I appear to be having a similar problem, except it seems to happen only when the activity is coming back after it has been left unopened for a while.

Caused by java.lang.NullPointerException
    at activeandroid.Cache.getTableName (Cache.java:156)
    at com.activeandroid.query.From.toSql (From.java:146)
    at com.activeandroid.query.From.execute (From.java:205)

I think it looks to me like the tableInfo is null. Does the cache ever get rebuilt?

[tomrozb]

happen only when the activity is coming back after it has been left unopened for a while.

Yes it happens to me also. It's rather a rare and hard to reproduce crash but occurs constantly with almost exactly the same stack trace (Cache.java:156). Maybe launching from a 3rd party app is not the problem at all, just pointed it out to present the whole picture.

[daentech]

Have you added each of the model classes explicitly to the AA instance? I've just done that (as mentioned in the other threads) rather than using the automatic model detection and I'll see if the crashes still appear.

Edit: It looks like it's still happening despite adding the classes manually.

[tomrozb]

@daentech How to add them? Please give me some links with an example and I'll try.

[daentech]

I have tried it like the following, but it hasn't worked for me:

Configuration.Builder configurationBuilder = new Configuration.Builder(getApplicationContext());
        configurationBuilder.addModelClasses(
                MyObject1.class,
                MyObject2.class
        );
        ActiveAndroid.initialize(configurationBuilder.create());

[tomrozb]

@daentech Will this configuration prevent from scanning the entire apk for classes which extends Model or it's just hint to use some classes and scan for others?

I'll try to add this in the next release and see if it helps in any way.

[daentech]

I think it still does the scan. At least, I added a couple of classes to it and it still managed to find the others. Let me know your results.

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On Fri, Nov 28, 2014 at 6:29 PM, Tomasz Rozbicki notifications@github.com wrote:

@daentech Will this configuration prevent from scanning the entire apk for classes which extends Model or it's just hint to use some classes and scan for others?

I'll try to add this in the next release and see if it helps in any way.

Reply to this email directly or view it on GitHub: https://github.com/pardom/ActiveAndroid/issues/299#issuecomment-64915755

[tomrozb]

Nothing has changed, I can still see in crash reports this occurs exactly on the same line.

[daentech]

In the end I've done a pretty horrible hack to mitigate it. Using an ExceptionHandler to catch it, deal with just that particular one by relaunching the app clean and it seems to work. I couldn't however recommend that method in good faith :)

[tomrozb]

I can confirm this is not related to activities or different processes. It happens even in Services so it must be a bug in ActiveAndroid. @pardom do you know what might be wrong here?

[amolgupta]

I added the config to the manifest file to indicate the scan but still got this issue <meta-data android:name="AA_MODELS" android:value="xxx.xxxx.entities.Notification, xxx.xxx.entities.ActivityLog" />

[jlhonora]

Did you also increase the AA_DB_VERSION number after adding the models to your manifest?

[amolgupta]

Yes I did. I even cleared the data for the app. Its happenning consistently unlike for others in this thread.

[amolgupta]

I am testing my code on a Android 5.0 device and a Android 2.3 emulator. It crashes only on 2.3. Will look for a 2.3 device and post the result here.

[amolgupta]

So far it has crashed on ALL emulator but NO actual device. Tested on various versions of emulators and devices.

[pflammertsma]

We're seeing this crash in some production code on devices in the wild. The snapshot I'm looking at includes 136 devices, and of those devices I see at least Android 4.3 through to 5.0.2, including stock Nexus 4.

My particular crash occurs on this line, which is called through a Loader:

Uri uri = mContext.getContentResolver().insert(
        ContentProvider.createUri(ZoneInformation.class, null), cv);

We have initialized ActiveAndroid in our Application's onCreate():

@Override
public void onCreate() {
    super.onCreate();
    ActiveAndroid.initialize(this);
    //...
}

I haven't had any luck reproducing it; it only happens in the wild.

[tomrozb]

I've tried to fix it but without luck. I'm afraid this project may already be abandoned. The last commit is dated to Oct 7, 2014, there are 149 issues and 40 pull requests. I don't think this issue will be fixed soon.

[pflammertsma]

I believe I can give some insight into this issue. I noticed that the way in which URIs were being added into AA's ContentProvider were localized strings. It appears that by switching to the Turkish locale, i was being converted (only in some cases) to ı (note the missing dot on the i).

In my case, the UriMatcher contained a match for parkingzoneınformation, but the URI it was trying to match against was content://com.parkmobile.debug/parkingzoneinformation.

I'm trying to get to the bottom of this and will follow up when I find the root cause.

[pflammertsma]

The underlying problem appears to be in AA's ContentProvider class, in the onCreate() on line 51 and 55:

URI_MATCHER.addURI(sAuthority, tableInfo.getTableName().toLowerCase(), tableKey);
...
URI_MATCHER.addURI(sAuthority, tableInfo.getTableName().toLowerCase() + "/#", itemKey);

Changing capitalization using the default locale's may yield bad results. In Turkish, a lowercase I is not i, but ı. From the example in my previous comment, my table was being case converted from ParkingZoneInformation, which revealed the underlying problem.

The simple solution is to change these lines respectively to:

URI_MATCHER.addURI(sAuthority, tableInfo.getTableName().toLowerCase(Locale.ENGLISH), tableKey);
...
URI_MATCHER.addURI(sAuthority, tableInfo.getTableName().toLowerCase(Locale.ENGLISH) + "/#", itemKey);

There's another instance of this bug in createUri():

uri.append(Cache.getTableName(type).toLowerCase(Locale.ENGLISH));

We've made the fixes in our fork of ActiveAndroid.

Here's the specific patch commit: https://github.com/Pixplicity/ActiveAndroid/commit/dbf35f42ddd91e2a4f7da16f6bde18b10db9051d