Flink第一個簡單的demo ，wordCount

該問題參考引用如下：

https://blog.csdn.net/dax1n/article/details/70211035

自身程式碼中問題：

package cetc.flink

import org.apache.flink.api.scala.ExecutionEnvironment

object FlinKMain {

  def main(args: Array[String]): Unit = {
    // 1.設定執行環境
    val env = ExecutionEnvironment.getExecutionEnvironment

    //2.創造測試資料
 

    val text = env.fromElements("To be, or not to be,that is the question")

    //3.進行wordcount運算
    val counts = text.flatMap(_.toLowerCase.split("\\W+"))
      .map((_, 1)).groupBy(0).sum(1)
    //4.列印測試結構
    counts.print()
    
  }
  
}

執行時候出錯如下：

Error:(13, 32) could not find implicit value for evidence parameter of type org.apache.flink.api.common.typeinfo.TypeInformation[String]
    val text = env.fromElements("To be, or not to be,that is the question")
Error:(13, 32) 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.
    val text = env.fromElements("To be, or not to be,that is the question")
 

解決問題：

這是因為在當前環境之下找到不到scala的包，引入如下宣告即可

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

產生這個問題的原因（官網說明）：

1：A frequent reason if that the code that generates the TypeInformation has not been imported. Make sure to import the entire flink.api.scala package.

2：Another common cause are generic methods, which can be fixed as described in the following section.

 

我碰到的是問題1的情況。