Logging in with the Facebook Android SDK and Proguard

Question

I have created a Android application with the Facebook Android SDK 3.0.

I created a working application (when running from Eclipse). It will create a Facebook session (with com.facebook.UiLifecycleHelper) and a login button (with com.facebook.LoginButton) so that the user can login into Facebook. The Facebook authentication dialog is showing and after filling in the credentials the login button will show that the user is logged in into Facebook.

So, far everything works fine, but when I'm making a release build (with Proguard enabled) I get the following exception:

E/AndroidRuntime(14690): FATAL EXCEPTION: main
E/AndroidRuntime(14690): com.facebook.FacebookException: Unable to save session.
E/AndroidRuntime(14690):    at com.facebook.Session.saveSession(Session.java:673)
E/AndroidRuntime(14690):    at com.facebook.UiLifecycleHelper.onSaveInstanceState(UiLifecycleHelper.java:124)
E/AndroidRuntime(14690):    at com.peerkesoftware.blockcrusher.MorburActivity.onSaveInstanceState(MorburActivity.java:175)
E/AndroidRuntime(14690):    at android.app.Activity.performSaveInstanceState(Activity.java:1147)
E/AndroidRuntime(14690):    at android.app.Instrumentation.callActivityOnSaveInstanceState(Instrumentation.java:1216)
E/AndroidRuntime(14690):    at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3253)
E/AndroidRuntime(14690):    at android.app.ActivityThread.handleStopActivity(ActivityThread.java:3312)
E/AndroidRuntime(14690):    at android.app.ActivityThread.access$900(ActivityThread.java:150)
E/AndroidRuntime(14690):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1271)
E/AndroidRuntime(14690):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(14690):    at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(14690):    at android.app.ActivityThread.main(ActivityThread.java:5191)
E/AndroidRuntime(14690):    at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(14690):    at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(14690):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
E/AndroidRuntime(14690):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
E/AndroidRuntime(14690):    at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(14690): Caused by: java.io.NotSerializableException: com.facebook.internal.SessionTracker$CallbackWrapper
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1364)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481)
E/AndroidRuntime(14690):    at java.util.ArrayList.writeObject(ArrayList.java:644)
E/AndroidRuntime(14690):    at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(14690):    at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1053)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1404)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeFieldValues(ObjectOutputStream.java:979)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:368)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1074)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1404)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1671)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1517)
E/AndroidRuntime(14690):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1481)
E/AndroidRuntime(14690):    at com.facebook.Session.saveSession(Session.java:671)
E/AndroidRuntime(14690):    ... 16 more

I already tried adding some Proguard rules, but no luck resolving this issue:

-keep class com.facebook.*
-keep class com.facebook.android.*
-keep class android.webkit.WebViewClient
-keep class * extends android.webkit.WebViewClient
-keepclassmembers class * extends android.webkit.WebViewClient { 
    <methods>;  }

Does anybody have any idea how to resolve this problem?

Answer 1

The key is likely to be the NotSerializableException in your stack trace.

You are already along the right lines with the rule set. Have a look at this Proguard documentation, in particular the section 'Processing serializable classes'.

The simplest example you can try from there is:

-keepclassmembers class * implements java.io.Serializable
{
    private static final java.io.ObjectStreamField[] serialPersistentFields;
    private void writeObject(java.io.ObjectOutputStream);
    private void readObject(java.io.ObjectInputStream);
    java.lang.Object writeReplace();
    java.lang.Object readResolve();
}

but they expand on this and add more complexity.

I've seen something similar with Android's AIDL and the Parcelable interface, which is a different instance of serialisation (passing objects over a remote API). Proguard changes the class names, meaning that it can no longer find the expected classes to construct.