CODEWITHSUNDEEP
javaandroidmobile
NSchulze
NSchulze

Reputation: 177

Puzzling java.lang.NullPointerException in Android App

I'm currently working on an Android App and, almost every time I use it, I get a an error. Most of the time it doesn't crash the app, but it is still frustrating that I'm seeing this error. I thought I did a check for it, but I could be wrong. Thanks for the help! The relevant code is below. (It's relevant because the line outside the if statement is throwing the NullPointerException.)

 Activity activity;     

 if(activity == null)
 {
   activity = new Activity();
 }

 Intent intent = new Intent(activity, Service.class);

Upvotes: 0

Views: 344

Answers (3)

xeed
xeed

Reputation: 947

As postet previously there is more to initiate for an activity than calling the constructor. Probably you get a null pointer exception deep within the Intent Constructer where it is trying to get some of the Activityinformation usually provided.

If you really want to create a Service, heres a link for starting a Service, but you should really read the whole article and probably some more of the activity lifecycle ressources.

http://developer.android.com/guide/topics/fundamentals/services.html#StartingAService

Upvotes: 0

kabuko
kabuko

Reputation: 36302

You should post some more of the surrounding code, but your problem is that creating new Intent requires a valid Context. Usually you create an Intent within an Activity (or Service or BroadcastReceiver) class so you can just do something like:

Intent intent = new Intent(this, Service.class);

Occasionally you'll create it somewhere else and pass it that valid Context, but you should pretty much never create an Activity by calling the constructor directly. There's a lot of other initialization necessary to make it useful.

Upvotes: 0

Kevin Parker
Kevin Parker

Reputation: 17206

You don't usually instantiate the Activity class in this manner. Please see the documentation on the Android Activity class here:

http://developer.android.com/reference/android/app/Activity.html

Upvotes: 3

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