GamesNativeSDK "Could not load additional classes from embedded jar."

Question

I'm trying to add Google Games Services to my native Android game. gpg::GamesServices::Builder::Create is returning NULL and the following is printed in logcat:

E/GamesNativeSDK(pid): Error emptying previous jar directory.
E/GamesNativeSDK(pid): Could not load additional classes from embedded jar.

My native code is very simple:

gpg::AndroidInitialization::JNI_OnLoad( javaVM );
gpg::AndroidPlatformConfiguration platform_configuration;
platform_configuration.SetActivity( activity );
gpg::GamesServices::Builder builder;
service = builder
    .SetOnAuthActionStarted([this](gpg::AuthOperation op) { OnAuthActionStarted(op); })
    .SetOnAuthActionFinished([this](gpg::AuthOperation op, gpg::AuthStatus status) { OnAuthActionFinished(op, status); })
    .EnableSnapshots()
    .Create(platform_configuration);

My project.properties contains:

android.library.reference.3=extras/play_services/library

Which is where I put the Google Play Services library. When I run ant, I see it's including extras/play_services/library/bin/classes.jar and lib/google-play-services.jar

I'm not using proguard.

Answer 1

Turns out you have to call AndroidInitialization::JNI_OnLoad from within JNI_OnLoad. You can't call it arbitrarily when you want to initialize GPG.

PieNoon has a great example of using JNI_OnLoad: https://github.com/google/pienoon/blob/master/src/gpg_manager.cpp