Flink Scala API“参数不足”

Question

我在使用Apache Flink Scala API时遇到问题

例如，即使我从官方文档中获取示例，scala编译器也会给我大量的编译错误。

代码：

object TestFlink {

  def main(args: Array[String]) {
    val env = ExecutionEnvironment.getExecutionEnvironment
    val text = env.fromElements(
      "Who's there?",
      "I think I hear them. Stand, ho! Who's there?")

    val counts = text.flatMap { _.toLowerCase.split("\\W+") filter { _.nonEmpty } }
      .map { (_, 1) }
      .groupBy(0)
      .sum(1)

    counts.print()

    env.execute("Scala WordCount Example")
  }
}

Scala IDE为行val text=env输出以下内容。fromElements

Multiple markers at this line
  - not enough arguments for method fromElements: (implicit evidence$14: scala.reflect.ClassTag[String], implicit evidence$15: 
   org.apache.flink.api.common.typeinfo.TypeInformation[String])org.apache.flink.api.scala.DataSet[String]. Unspecified value parameter evidence$15.
  - could not find implicit value for evidence parameter of type org.apache.flink.api.common.typeinfo.TypeInformation[String]
  - could not find implicit value for evidence parameter of type org.apache.flink.api.common.typeinfo.TypeInformation[String]
  - not enough arguments for method fromElements: (implicit evidence$14: scala.reflect.ClassTag[String], implicit evidence$15: 
   org.apache.flink.api.common.typeinfo.TypeInformation[String])org.apache.flink.api.scala.DataSet[String]. Unspecified value parameter evidence$15.

这不仅仅是frommelements方法：即使我从文件中读取数据，然后尝试做一些像ds这样简单的事情。地图（r）=

Multiple markers at this line
    - not enough arguments for method map: (implicit evidence$4: org.apache.flink.api.common.typeinfo.TypeInformation[K], implicit 
     evidence$5: scala.reflect.ClassTag[K])org.apache.flink.api.scala.DataSet[K]. Unspecified value parameters evidence$4, evidence$5.
    - could not find implicit value for evidence parameter of type org.apache.flink.api.common.typeinfo.TypeInformation[K]
    - could not find implicit value for evidence parameter of type org.apache.flink.api.common.typeinfo.TypeInformation[K]
    - not enough arguments for method map: (implicit evidence$4: org.apache.flink.api.common.typeinfo.TypeInformation[K], implicit 
     evidence$5: scala.reflect.ClassTag[K])org.apache.flink.api.scala.DataSet[K]. Unspecified value parameters evidence$4, evidence$5.

我尝试了Flink的两个版本：Maven Central的0.8.1版本和github存储库中最新的版本。

我运行的是Windows7，scala 2.10.4，JDK1.7.0_25，scala IDE版本是3.0.3-20140327-1716-Typesafe，位于Eclipse4.3.0之上

我做错了什么？




Answer 1

您需要将以下导入添加到代码中：

import org.apache.flink.api.scala._ 

那么这个例子就行了。