java.lang.NullPointerException

[Muhammad Riaz]

`
BillingProcessor bp

bp = new BillingProcessor(this, BuildConfig.LICENSE_KEY, this);

    bp.initialize();

`

java.lang.NullPointerException: 
  at com.xyz.onBillingInitialized (InAppActivity.java:856)
  at com.anjlab.android.iab.v3.BillingProcessor$HistoryInitializationTask.onPostExecute (BillingProcessor.java:156)
  at com.anjlab.android.iab.v3.BillingProcessor$HistoryInitializationTask.onPostExecute (BillingProcessor.java:127)
  at android.os.AsyncTask.finish (AsyncTask.java:636)
  at android.os.AsyncTask.access$500 (AsyncTask.java:177)
  at android.os.AsyncTask$InternalHandler.handleMessage (AsyncTask.java:653)
  at android.os.Handler.dispatchMessage (Handler.java:102)
  at android.os.Looper.loop (Looper.java:145)
  at android.app.ActivityThread.main (ActivityThread.java:6917)
  at java.lang.reflect.Method.invoke (Native Method)
  at java.lang.reflect.Method.invoke (Method.java:372)
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run (ZygoteInit.java:1404)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1199)

@OverRide
public void onBillingInitialized() {
if(bp.isPurchased("android.test.purchased")){ // this is the line where play consol report NullPointerException .
PrefManager.with(this).save("purchased", true);
}
}