Hello, In your case the key's type is String, not byte array, so you need to override the following property:
key.serializer.class -> "kafka.serializer.StringEncoder" Details of the producer configs can be found: http://kafka.apache.org/documentation.html#producerconfigs On Wed, Jan 22, 2014 at 4:51 PM, Cassa L <lcas...@gmail.com> wrote: > Hi all, > I am a new user of Kafka. I tried Java example of it and it worked great. > Now when I tried to write to a Producer (Java) and send ByteArray to it as > a data, I get ClassCastException as below > > java.lang.ClassCastException: java.lang.String cannot be cast to [B > at kafka.serializer.DefaultEncoder.toBytes(Encoder.scala:34) > at > > kafka.producer.async.DefaultEventHandler$$anonfun$serialize$1.apply(DefaultEventHandler.scala:128) > at > > kafka.producer.async.DefaultEventHandler$$anonfun$serialize$1.apply(DefaultEventHandler.scala:125) > at > > scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:233) > at > > scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:233) > at > > scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:34) > at scala.collection.mutable.WrappedArray.foreach(WrappedArray.scala:33) > at > scala.collection.TraversableLike$class.map(TraversableLike.scala:233) > at scala.collection.mutable.WrappedArray.map(WrappedArray.scala:33) > at > > kafka.producer.async.DefaultEventHandler.serialize(DefaultEventHandler.scala:125) > at > > kafka.producer.async.DefaultEventHandler.handle(DefaultEventHandler.scala:52) > at kafka.producer.Producer.send(Producer.scala:76) > at kafka.javaapi.producer.Producer.send(Producer.scala:33) > > ===================== > I am setting up Kafka properties as below - > > props.put("serializer.class", "kafka.serializer.DefaultEncoder"); > props.put("partitioner.class", > "kafka.producer.DefaultPartitioner"); > > ===================== > And I am sending data to producer as mentioned below - > KeyedMessage<String,byte[]> data = new KeyedMessage<String, byte[]> > ("Topic", key, bytearray ); > producer.send(data); > > Can someone help me understand where actually this ClassCast problem is > occurring? > > ..lCassa > -- -- Guozhang
