Android crash

[nuzelac]

Hi,

I have migrated IAP to RevenueCat in my app. iOS works fine, but Android works only on 1st launch after deleting the app from test device. Looks like there's some bogus data in SharedPreferences. Any suggestions what I could try?

E/AndroidRuntime(30679): FATAL EXCEPTION: pool-8-thread-1
E/AndroidRuntime(30679): Process: net.poopmap, PID: 30679
E/AndroidRuntime(30679): java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Set
E/AndroidRuntime(30679): 	at android.app.SharedPreferencesImpl.getStringSet(SharedPreferencesImpl.java:293)
E/AndroidRuntime(30679): 	at com.revenuecat.purchases.DeviceCache.getPreviouslySentHashedTokens$purchases_release(DeviceCache.kt:100)
E/AndroidRuntime(30679): 	at com.revenuecat.purchases.DeviceCache.cleanPreviouslySentTokens(DeviceCache.kt:127)
E/AndroidRuntime(30679): 	at com.revenuecat.purchases.Purchases$updatePendingPurchaseQueue$1.run(Purchases.kt:926)
E/AndroidRuntime(30679): 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
E/AndroidRuntime(30679): 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
E/AndroidRuntime(30679): 	at java.lang.Thread.run(Thread.java:764)

[nuzelac]

Please disregard, this is happening because I'm using flutter's shared_preferences plugin, which converts Set to List when you read from it. By default that plugin uses its own shared prefs xml but I forked it to read default shared prefs so that's why it interferes with RevenueCat.

[diegocom]

@nuzelac Hi, I have the same problem. I need to read the Android default shared preferences and not the flutter ones, but after reading them the app will crash on subsequent launches. How did you solve?

[nuzelac]

Hi @diegocom I'm running a fork of shared_preferences plugin so that I can read default Android prefs.
This migration of Set to List in getAllPrefs method will cause the crash on next launch so I simply ignore this migration when prefix length 0 (e.g. I'm trying to read all prefs, not just Flutter ones).

You can check my commit here:
nuzelac/plugins@ae51d83

[diegocom]

@nuzelac Great, it works! You saved my day

[vegaro]

Is there anything we can do on our side to prevent this from happening for future developers? I am not sure I completely understand what's going on 😆 @nuzelac @diegocom

[nuzelac]

@vegaro Hah, it's a very specific issue, I had to look through my old commits to see how I fixed this. 😀

The thing is, Flutter's shared_preferences plugin doesn't allow you to read any arbitrary prefs from Android, it adds a Flutter specific prefix by default and will only read prefs with the prefix. I think it will also use separate XML, but not certain about that.
I had a Xamarin app that used prefs and wanted to read these back when I migrated my app to Flutter.

If you hack around it (to make this prefix optional) you can read anything but the getter has some internal logic that converts Set to List serialized into String. This will touch RC prefs data and crash your SDK on launch next time.

https://github.com/flutter/plugins/blob/master/packages/shared_preferences/shared_preferences/android/src/main/java/io/flutter/plugins/sharedpreferences/MethodCallHandlerImpl.java#L181-L196

Honestly, I wouldn't expect you to handle this case gracefully since it's not usual behavior 🤔