Error in twitter streaming - twitter

Question

I am writing a twitter connector using spark streaming.
I am facing the follwing exception
ERROR ReceiverTracker: Deregistered receiver for stream 0: Restarting
receiver with delay 2000ms: Error starting Twitter stream -
java.lang.NullPointerException
at org.apache.spark.streaming.twitter.TwitterReceiver.onStart(TwitterInputDStream.scala:89)
at org.apache.spark.streaming.receiver.ReceiverSupervisor.startReceiver(ReceiverSupervisor.scala:121)
at org.apache.spark.streaming.receiver.ReceiverSupervisor$$anonfun$restartReceiver$1.apply$mcV$sp(ReceiverSupervisor.scala:159)
at org.apache.spark.streaming.receiver.ReceiverSupervisor$$anonfun$restartReceiver$1.apply(ReceiverSupervisor.scala:152)
at org.apache.spark.streaming.receiver.ReceiverSupervisor$$anonfun$restartReceiver$1.apply(ReceiverSupervisor.scala:152)
at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
at scala.concurrent.impl.ExecutionContextImpl$$anon$3.exec(ExecutionContextImpl.scala:107)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Below is the relavent code snippet.
val config = new twitter4j.conf.ConfigurationBuilder()
.setOAuthConsumerKey("*********************")
.setOAuthConsumerSecret("**********************************************")
.setOAuthAccessToken("****************************************************")
.setOAuthAccessTokenSecret("**********************************************************")
.build
val twitter_auth = new TwitterFactory(config)
val a = new twitter4j.auth.OAuthAuthorization(config)
val atwitter : Option[twitter4j.auth.Authorization] = Some(twitter_auth.getInstance(a).getAuthorization())
val sparkConf = new SparkConf().setAppName("TwitterPopularTags").setMaster("local[*]")
val ssc = new StreamingContext(sparkConf, Seconds(2))
// ssc.checkpoint("D:/test")
val stream = TwitterUtils.createStream(ssc, atwitter, null, StorageLevel.MEMORY_AND_DISK_2)
val hashTags = stream.map(status => status.getUser().getName())
hashTags.foreachRDD(rdd => {
rdd.foreach(println)
})
ssc.start()
ssc.awaitTermination()
Can anyone help me to solve this issue?
Thanks :)

Answer 1

Going to the line where the exception is thrown, we can see:
if (filters.size > 0) {
For that line to throw a NPE, filters has to be null, which is exactly what's happening on the instantiation of the TwitterStream:
val stream = TwitterUtils.createStream(ssc, atwitter, null, StorageLevel.MEMORY_AND_DISK_2)
Being filter a sequence, initialize it with Seq() instead of null.