Getting Run time exception

[KhadkaRabindra]

Fatal Exception: java.lang.RuntimeException An error occured while executing doInBackground() android.os.AsyncTask$3.done

Caused by java.lang.NullPointerException Attempt to invoke interface method 'java.util.Iterator java.util.List.iterator()' on a null object reference com.ice.restring.StringsLoaderTask.doInBackground

com.ice.restring.StringsLoaderTask.doInBackground (StringsLoaderTask.java:36) com.ice.restring.StringsLoaderTask.doInBackground (StringsLoaderTask.java:16) android.os.AsyncTask$2.call (AsyncTask.java:292) java.util.concurrent.FutureTask.run (FutureTask.java:237) java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1112) java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:587) java.lang.Thread.run (Thread.java:818)