Android: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference

[costimuraru]

Awesome job on this library!
I managed to get it work on Desktop, but on Android I'm getting a NullPointerException.

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
        at com.facebook.login.LoginClient.getLogger(LoginClient.java:373)

in com.facebook.login.LoginClient.getLogger pendingRequest.getApplicationId() seems to be null.

The code I'm using:

Gdx.app.setLogLevel(Application.LOG_DEBUG);
GDXFacebookConfig config = new GDXFacebookConfig();
config.APP_ID = "replaced-this-with-actual-app-id"; // required
config.PREF_FILENAME = ".facebookSessionData"; // optional
config.GRAPH_API_VERSION = "v2.6"; // optional, default is v2.6
GDXFacebook facebook = GDXFacebookSystem.install(config);

Array<String> permissions = new Array<String>();
permissions.add("email");
permissions.add("public_profile");
permissions.add("user_friends");

facebook.signIn(SignInMode.READ, permissions, new GDXFacebookCallback<SignInResult>() {
    @Override
    public void onSuccess(SignInResult result) {
        // Login successful
    }

    @Override
    public void onError(GDXFacebookError error) {
        // Error handling
    }

    @Override
    public void onCancel() {
        // When the user cancels the login process
    }

    @Override
    public void onFail(Throwable t) {
        // When the login fails
    }
});

Did I miss something

Full stack trace:

D/gdx-facebook (1.4.1): gdx-facebook (1.4.1) for Android installed successfully.
D/gdx-facebook (1.4.1): Could not load existing accessToken.
D/gdx-facebook (1.4.1): Starting GUI sign in.
I/OMXClient: IOmx service obtained
I/BaseScreen: Disposing.
I/AndroidInput: sensor listener tear down
I/AndroidGraphics: paused
W/com.facebook.appevents.internal.ActivityLifecycleTracker: Unexpected activity pause without a matching activity resume. Logging data may be incorrect. Make sure you call activateApp from your Application's onCreate method
W/ActivityThread: handleWindowVisibility: no activity for token android.os.BinderProxy@563aa9d
I/OMXClient: IOmx service obtained
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.ph.myapp, PID: 9529
    java.lang.RuntimeException: Unable to resume activity {com.ph.myapp/com.facebook.FacebookActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
        at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3784)
        at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3816)
        at android.app.servertransaction.ResumeActivityItem.execute(ResumeActivityItem.java:51)
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:145)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:70)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
        at com.facebook.login.LoginClient.getLogger(LoginClient.java:373)
        at com.facebook.login.LoginClient.tryCurrentHandler(LoginClient.java:261)
        at com.facebook.login.LoginClient.tryNextHandler(LoginClient.java:216)
        at com.facebook.login.LoginClient.authorize(LoginClient.java:121)
        at com.facebook.login.LoginClient.startOrContinueAuth(LoginClient.java:102)
        at com.facebook.login.LoginFragment.onResume(LoginFragment.java:153)
        at android.support.v4.app.Fragment.performResume(Fragment.java:2133)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1156)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1295)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1277)
        at android.support.v4.app.FragmentManagerImpl.dispatchResume(FragmentManager.java:2164)
        at android.support.v4.app.FragmentController.dispatchResume(FragmentController.java:223)
        at android.support.v4.app.FragmentActivity.onResumeFragments(FragmentActivity.java:509)
        at android.support.v4.app.FragmentActivity.onPostResume(FragmentActivity.java:498)
        at android.app.Activity.performResume(Activity.java:7317)
        at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3776)
        at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3816) 
        at android.app.servertransaction.ResumeActivityItem.execute(ResumeActivityItem.java:51) 
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:145) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:70) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
I/Process: Sending signal. PID: 9529 SIG: 9
Application terminated.

Am I doing something wrong?

[costimuraru]

After some good old debugging, seems to work fine after I add:

FacebookSdk.setApplicationId(getString(R.string.facebook_app_id));

in my class AndroidLauncher extends com.badlogic.gdx.backends.android.AndroidApplication

Shouldn't FacebookSdk.setApplicationId be performed by the gdx-facebook library or by the facebook android library itself?
Or should we add this to the wiki.

Perhaps I'm missing something here... :D

[TomGrill]

No idea what might be wrong. Did you add the app id to the AndroidManifest.xml?

If you provide a working project example I can look further into it.