如何克服scala nosuchmethoderror？

Question

刚刚开始使用scala和spark来运行这个简单的程序：

package spark.example

import org.apache.spark.SparkContext
import org.apache.spark.SparkContext._
import org.apache.spark.SparkConf

object SparkGrep {
  def main(args: Array[String] = Array("default argument")) {
    val conf = new SparkConf().setAppName("SparkGrep").setMaster("localhost")
    val sc = new SparkContext(conf)
    val inputFile = sc.textFile("/Users/eugene/Downloads/hello.txt").cache()
    val matchTerm : String = "hello"
    val numMatches = inputFile.filter(line => line.contains(matchTerm)).count()
    println("%s lines in %s contain %s".format(numMatches, args(1), matchTerm))
    System.exit(0)
  }
}

Exception in thread "main" java.lang.NoSuchMethodError: scala.collection.immutable.HashSet$.empty()Lscala/collection/immutable/HashSet;
    at akka.actor.ActorCell$.<init>(ActorCell.scala:305)
    at akka.actor.ActorCell$.<clinit>(ActorCell.scala)
    at akka.actor.RootActorPath.$div(ActorPath.scala:152)
    at akka.actor.LocalActorRefProvider.<init>(ActorRefProvider.scala:465)
    at akka.remote.RemoteActorRefProvider.<init>(RemoteActorRefProvider.scala:124)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at akka.actor.ReflectiveDynamicAccess$$anonfun$createInstanceFor$2.apply(DynamicAccess.scala:78)
    at scala.util.Try$.apply(Try.scala:192)
    at akka.actor.ReflectiveDynamicAccess.createInstanceFor(DynamicAccess.scala:73)
    at akka.actor.ReflectiveDynamicAccess$$anonfun$createInstanceFor$3.apply(DynamicAccess.scala:84)
    at akka.actor.ReflectiveDynamicAccess$$anonfun$createInstanceFor$3.apply(DynamicAccess.scala:84)
    at scala.util.Success.flatMap(Try.scala:231)
    at akka.actor.ReflectiveDynamicAccess.createInstanceFor(DynamicAccess.scala:84)
    at akka.actor.ActorSystemImpl.<init>(ActorSystem.scala:550)
    at akka.actor.ActorSystem$.apply(ActorSystem.scala:111)
    at akka.actor.ActorSystem$.apply(ActorSystem.scala:104)
    at org.apache.spark.util.AkkaUtils$.createActorSystem(AkkaUtils.scala:96)
    at org.apache.spark.SparkEnv$.create(SparkEnv.scala:126)
    at org.apache.spark.SparkContext.<init>(SparkContext.scala:139)
    at spark.example.SparkGrep$.main(SparkGrep.scala:14)
    at spark.example.SparkGrep.main(SparkGrep.scala)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

Answer 1

这是一个很常见的错误，因为它忘记了Spark是针对Scala的旧版本（从Spark 1.6.1开始的2.10.x(Spark 2.0很快会对此进行更改））编译的。

更改您的代码以使用所述版本进行编译应该可以解决您的运行时问题。