NullPointerException

Question

can someone please tell me why in the following line the code throws a NullPointer.

public List<ApplicationInfo> getAppInfos(Context myContext) {
    PackageManager pm = myContext.getPackageManager();
    List<ApplicationInfo> appInfo = pm.getInstalledApplications(PackageManager.GET_META_DATA);
    Collections.sort(appInfo, new ApplicationInfo.DisplayNameComparator(pm)); //throws Nullpointer
    return appInfo;
}

I try to call this method from a seperate Thread (not the UIThread). But i passed the Context from my Activity... If i call this method from my Activity(without passing the context for sure) it works fine.

I appreciate any help.

Update regarding Comment:

Thank you for your respone. That's a tricky Thing. Because the Code runs fine on Emulator with API 17 but not on my real device. And i got a cool Alcatel phone which is, for me, really tricky to get it run for usb Debugging(i think not just for me, the Support is awful). Under some circumstances i achieved to Crash the app on the Emulator as well. I only remember a nullpointerexception, but maybe i mixed something. But what i can say is that when i comment the Collections.sort... out. The app runs on the device as well. I'm sorry for being so confusing right now. The only Thing i can say is that this line crashes my app on my device, but not on my Emulator and only if i call this from an seperate Thread.

I instantiate Context like this:

final Context myContext = MyActivity.this;

And in the Thread i just call the method like this:

List<ApplicationInfo> myList = getAppInfos(myContext);

PHONE and Emulator are running with same Android Version!

Answer 1

You are getting the nullPointerException because pm in:

PackageManager pm = myContext.getPackageManager();

is returning null . Without seeing how you get your context, it's hard to say why sometimes it's null and sometimes it's not.