Flink Scala API的“参数不足" [英] Flink Scala API "not enough arguments"
问题描述
我在使用Apache Flink Scala API时遇到麻烦
I'm having troubles using Apache Flink Scala API
例如,即使我从官方文档中获取示例,scala编译器也会给我带来大量的编译错误.
For example, even when I take the examples from the official documentation, the scala compiler gives me tons of compilation errors.
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在val text = env.fromElements
Scala IDE outputs the following for the line val text = env.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.
这不仅是fromElements
方法:即使我从文件中读取内容,然后尝试执行与ds.map(r => r)
一样简单的操作,我也会得到非常相似的内容
It's not just fromElements
method: even if I read from a file and then try to do something as simple as ds.map(r => r)
, I get something very similar
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和github存储库中最新鲜的一个.
I tried two versions of Flink: 0.8.1 from Maven Central and the most fresh one from the github repository.
我正在运行Windows 7,scala 2.10.4,jdk 1.7.0_25,Scala IDE版本是Eclipse 4.3.0之上的3.0.3-20140327-1716-Typesafe
I'm running Windows 7, scala 2.10.4, jdk 1.7.0_25, Scala IDE version is 3.0.3-20140327-1716-Typesafe on top of Eclipse 4.3.0
我在做什么错了?
推荐答案
您需要在代码中添加以下导入:
You need to add the following import to your code:
import org.apache.flink.api.scala._
然后该示例起作用.
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