KafkaProducer [String，String]类型的表达式不符合预期类型Null

Question

我希望能够从函数producer初始化变量setProducer。

object MyObj { 
  var producer = null                                                                                                                  

  def setProducer(p: KafkaProducer[String,String]): Unit = {           
    producer = p                                                       
  }   

  //...
}

然而它说Expression of type KafkaProducer[String,String] doesn't conform to expected type Null。

那么，我该如何初始化producer？

Answer 1

您需要为变量提供类型，例如：

object MyObj { 
  var producer: KafkaProducer[String,String] = null                                                                                                                  

  def setProducer(p: KafkaProducer[String,String]): Unit = {           
    producer = p                                                       
  }   

  //...
}