null pointer on calling ContentResolver.setSyncAutomatically android

Question

I want to sync my local app database with my remote server database using android sync adapter. I followed all steps mentioned in developer website and I double checked every thing. but I get null pointer when lines below executed in my MainActivity oncreate:

mAccount = CreateSyncAccount(this);
ContentResolver.setSyncAutomatically(mAccount, AUTHORITY, true);

here is my stacktrace:

12-05 15:05:40.099: E/AndroidRuntime(13641): FATAL EXCEPTION: main
12-05 15:05:40.099: E/AndroidRuntime(13641): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mobinMahsaz.dortan/com.mobinMahsaz.dortan.MainActivity2}: java.lang.NullPointerException
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.os.Handler.dispatchMessage(Handler.java:99)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.os.Looper.loop(Looper.java:130)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.app.ActivityThread.main(ActivityThread.java:3687)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at java.lang.reflect.Method.invokeNative(Native Method)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at java.lang.reflect.Method.invoke(Method.java:507)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at dalvik.system.NativeStart.main(Native Method)
12-05 15:05:40.099: E/AndroidRuntime(13641): Caused by: java.lang.NullPointerException
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.os.Parcel.readException(Parcel.java:1328)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.os.Parcel.readException(Parcel.java:1276)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.content.IContentService$Stub$Proxy.setSyncAutomatically(IContentService.java:568)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.content.ContentResolver.setSyncAutomatically(ContentResolver.java:1047)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at com.mobinMahsaz.dortan.MainActivity2.onCreate(MainActivity2.java:283)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-05 15:05:40.099: E/AndroidRuntime(13641):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
12-05 15:05:40.099: E/AndroidRuntime(13641):    ... 11 more

I can't find any documentation that states what is the reason of this exception.

EDIT: After reading ContentResolver documentation I find out null pointer cause by getcontentService().

Answer 1

It could be different for you, but for me this was caused because I had a null mAccount object. I had incorrectly assumed that if AccountManager.addAccountExplicitly returned false then there had been a fatal error, so was returning a null Account from my CreateSyncAccount function in that situation.