Question

无法解析Foreach符号

import java.util._
import org.apache.kafka.clients.consumer._
import org.apache.kafka.common.serialization.Deserializer

object ConsumerExample {

  def main(args: Array[String]): Unit = {

    val T_Name = "CarSensor"
    val T_Group_Name = "CarSensorGroup"
    val props = new Properties()

    props.put("bootstrap.servers", "localhost:9092,localhost:9093,localhost:9094")
    props.put("group.id",T_Group_Name)
    props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer")
    props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer")

    val Kafka_Consumer=new KafkaConsumer[String,String](props)
    Kafka_Consumer.subscribe (Arrays.asList(T_Name))
    while(true)
    {
      val Consumer_Record=Kafka_Consumer.poll(100) //ConsumerRecords Object
      //  val RecordList=Consumer_Record.toString
      for( i <- Consumer_Record)
      { //**This place is where Cannot resolve symbol for Foreach issue shows up for <- symbol.**
        println("Supplier id = "+String.valueOf(i.value().getID())+ "Supplier name = " +i.value().getID())
      }
    }
  }
}

在很多例子中，我已经使用<-符号来起作用。我认为这是Intelliji的问题，然后重新启动。我猜这是将对象强制转换为其他类型的问题。

Answer 1

  Consumer_Record.forEach(i => {
    println("Supplier id = "+String.valueOf(i.value().getID())+ "Supplier name = " +i.value().getID())
  })

对我来说很好。

String除外，没有getID()方法。

如果要使用for(i <- Consumer_Record.asScala)语法，则可以使用for，但是必须添加import scala.collection.JavaConverters._。

Answer 2

val Kafka_Consumer=new KafkaConsumer[String,String](props)

Kafka_Consumer.subscribe(Arrays.asList(T_Name))

while(true) {

  val Consumer_Record=Kafka_Consumer.poll(100) //ConsumerRecords Object

  for( i <- Consumer_Record.asScala) {
    println("Supplier id = "+String.valueOf(i.value())+ " Supplier name = " +i.key())
  }
}

尝试遍历消费者记录的

2 个答案: