Chill-kryo exception

Question

I am trying to run sample code for Chill-Scala from this

I have two classes of dummy cases

one - User

@SerialVersionUID(1) case class User(name :String, age : Int) extends Serializable 

and the other is Student

 @SerialVersionUID(2) case class Student(sub : String , id : Int , user : User) extends Serializable 

here is my serialization code that i changed from this github twitter / chill repo example

 object SeriDeseri { private val kryo = { val a = KryoSerializer.registerAll val k = new Kryo a(k) k } def toBytes(student : Student): Array[Byte] = { println("********** serializing") val b = new ByteArrayOutputStream val o = new Output(b) kryo.writeObject(o, student) o.close() b.toByteArray } def fromBytes[Student](bytes: Array[Byte])(implicit m: Manifest[Student]): Option[Student] = { println("********** Deserializing") val i = new Input(bytes) try { val t = kryo.readObject(i, m.runtimeClass.asInstanceOf[Class[Student]]) Option(t) } catch { case NonFatal(e) => None } finally { i.close() } } } 

here is the code for my main class

 val user = new User( "Ahsen", 14) val stu = new Student("oop", 12, user) val serial : Array[Byte] = SeriDeseri.toBytes(stu) val deserial :Option[Student] = SeriDeseri.fromBytes(serial) val obj = deserial match{ case Some(objec) => println(objec) case None => println("----------- Nothing was deserialized") } 

Now the problem is when I run this code, it gives me java.lang.InstantiationError: scala.runtime.Nothing$ exception

here are the full stack traces

[info] Running kryotest.Main

********** serialization

********** Deserializing [error] (run-main-0) java.lang.InstantiationError: scala.runtime.Nothing $ java.lang.InstantiationError: scala.runtime.Nothing $ at scala.runtime. Nothing $ ConstructorAccess.newInstance (unknown) at com.esotericsoftware.kryo.Kryo $ DefaultInstantiatorStrategy $ 1.newInstance (Kryo.java:1193) at com.esotericsoftware.kryo.Kryo.newInstance (Kryo.java10 .kryo.serializers.FieldSerializer.create (FieldSerializer.java►47) at com.esotericsoftware.kryo.serializers.FieldSerializer.read (FieldSerializer.java►23) at com.esotericsoftware.kryo.Kryo.readObject (Kryo.java:657 ) at com.test.hcast_serializer.SeriDeseri $ .fromBytes (SeriDeseri.scala: 32) at kryotest.Main $ .delayedEndpoint $ kryotest $ Home $ 1 (Main.scala: 31) at kryotest.Main $ delayedInit $ body.apply (Main .scala: 9) at scala.Function0 $ class.apply $ mcV $ sp (Function0.scala: 40) at scala.runtime.AbstractFunction0.apply $ μV $ sp (AbstractFunc tion0.scala: 12) in scala.App $$ anonfun $ main $ 1.apply (App.scala: 76) in scala.App $$ anonfun $ main $ 1.apply (App.scala: 76) in scala.collection.immutable .List.foreach (List.scala: 383) at scala.collection.generic.TraversableForwarder $ class.foreach (TraversableForwarder.scala: 35) in scala.App $ class.main (App.scala: 76) in kryotest.Main $ .main (Main.scala: 9) at kryotest.Main.main (Main.scala) at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native method) in sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62) in sun. reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43) in java.lang.reflect.Method.invoke (Method.java:497) [trace] Stack trace offpressed: execute last compilation: execute for full output. java.lang.RuntimeException: non-zero exit code: 1 at scala.sys.package $ .error (package.scala: 27) [trace] Stack tracing suppressed: start last compilation: execute for full output. [error] (compile: execute) Zero exit code: 1 [error] Total time: 4 s, completed August 31, 2015 3:15:54 PM

Please tell me what am I doing wrong?

Edit: when I replaced the next line from fromBytes method

val t = kryo.readObject(i, m.runtimeClass.asInstanceOf[Class[Student]])

with

 val t = kryo.readClassAndObject(i).asInstanceOf[Student] 

I do not know what happened after the modification, but that did not give me an exception, but the method returned None instead of the object

after modification

 ********** serializing ********** Deserializing ----------- Nothing was deserialized 

Answer 1

Since the first line of the example in the git repository for your example says that Chill now supports Scala 2.11. Use it instead.

There is an easy way to serialize Scala objects using chill from twitter

here is what they said:

Cold bijection

Biopsies and injections are useful when considering serialization. If you have an injection from T to the [Byte] array, you have serialization. Also, if you have a Bijection between A and B, and serialization for B, then you have serialization for A. See BijectionEnrichedKryo for easy interaction between bijection and cold. KryoInjection: Simple Serialization in Bytes Arrays

KryoInjection is an injection from Any to the [Byte] array. Serialization using it:

import com.twitter.chill.KryoInjection

val bytes: Array [Byte] = KryoInjection (someItem) val tryDecode: scala.util.Try [Any] = KryoInjection.invert (bytes)

KryoInjection can be composed with Bijections and Injections from com.twitter.bijection.

So, I rewrite your main class:

 object Main extends App { val user = new User( "Ahsen", 14) val stu = new Student("oop", 12, user) val bytes: Array[Byte] = KryoInjection(stu) println("Serialized byte array:" + bytes) val tryDecode: scala.util.Try[Any] = KryoInjection.invert(bytes) println(tryDecode) } 

and for your build.sbt use this:

 "com.twitter" % "chill-bijection_2.11" % "0.7.0" 

And finally, I get this result:

 [info] Running chill.Main Serialized byte array:[ B@17e5b410 Success(Student(oop,12,User(Ahsen,14)))