KafkaProducer類型的表達式[字符串，字符串]不符合期望的類型空

Question

我希望能夠從函數setProducer初始化變量producer。

object MyObj { 
    var producer = null                             

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

    //... 
} 

但是它說的是Expression of type KafkaProducer[String,String] doesn't conform to expected type Null。

那麼，我該如何初始化producer？

Answer 1

您需要提供的變量類型，例如：

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

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

    //... 
}