1) 本地運行報錯：
Exception in thread "main" org.apache.spark.SparkException: A master URL must be set in your configuration
解決方案：
第一種， 在代碼里設置：
val conf= new SparkConf(). setAppName("SimpleApp"). setMaster("local")
第二種，在IDE里設置為本地單線程運行（-Dspark.master=local）
2) 調用函數出錯：
Exception in thread "main" java.lang.ExceptionInInitializerError
at main.scala.test$.main(test.scala:13)
at main.scala.test.main(test.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: org.apache.spark.SparkException: Only one SparkContext may be running in this JVM (see SPARK-2243). To ignore this error, set spark.driver.allowMultipleContexts = true. The currently running SparkContext was created at:
org.apache.spark.SparkContext.<init>(SparkContext.scala:80)
原因：main函數和另一個獨立的函數我都定義了SparkContext
解決：把main函數里面的SparkContext定義去掉。直接用函數里面的sc 即可。
3）自定義class名 與 Spark內置的類名 重復報錯。
Warning:(1, 64)
imported `NaiveBayes' is permanently hidden by definition of object NaiveBayes
import org.apache.spark.mllib.classification.{NaiveBayesModel, NaiveBayes}
^