我在添加jars之前都和题主一样。但是添加完jars之后出现了以下错误，能不能帮我看看哪里出了问题

[Jiawen-huang]

我在添加jars之前都和题主一样。但是添加完jars之后出现了以下错误，能不能帮我看看哪里出了问题
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
17/08/02 16:56:21 INFO SparkContext: Running Spark version 2.3.0-SNAPSHOT
17/08/02 16:56:22 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
17/08/02 16:56:23 WARN Utils: Your hostname, hjw-XiaoXin-700 resolves to a loopback address: 127.0.1.1; using 192.168.191.4 instead (on interface wlp2s0)
17/08/02 16:56:23 WARN Utils: Set SPARK_LOCAL_IP if you need to bind to another address
17/08/02 16:56:23 ERROR SparkContext: Error initializing SparkContext.
org.apache.spark.SparkException: A master URL must be set in your configuration
at org.apache.spark.SparkContext.(SparkContext.scala:368)
at org.apache.spark.examples.LogQuery$.main(LogQuery.scala:47)
at org.apache.spark.examples.LogQuery.main(LogQuery.scala)
17/08/02 16:56:23 ERROR Utils: Uncaught exception in thread main
java.lang.NullPointerException
at org.apache.spark.SparkContext.org$apache$spark$SparkContext$$postApplicationEnd(SparkContext.scala:2401)
at org.apache.spark.SparkContext$$anonfun$stop$1.apply$mcV$sp(SparkContext.scala:1890)
at org.apache.spark.util.Utils$.tryLogNonFatalError(Utils.scala:1331)
at org.apache.spark.SparkContext.stop(SparkContext.scala:1889)
at org.apache.spark.SparkContext.(SparkContext.scala:581)
at org.apache.spark.examples.LogQuery$.main(LogQuery.scala:47)
at org.apache.spark.examples.LogQuery.main(LogQuery.scala)
17/08/02 16:56:23 INFO SparkContext: Successfully stopped SparkContext
Exception in thread "main" org.apache.spark.SparkException: A master URL must be set in your configuration
at org.apache.spark.SparkContext.(SparkContext.scala:368)
at org.apache.spark.examples.LogQuery$.main(LogQuery.scala:47)
at org.apache.spark.examples.LogQuery.main(LogQuery.scala)