user1189582 user1189582 - 6 months ago 215
Java Question

Serialization in Java, invalid type code 00

I'm getting an error (java.io.StreamCorruptedException: invalid type code: 00) when reading in a serialised object. Here is the class that implements serializable:

package guts;

import cc.mallet.classify.*;
import java.io.*;


public class NaiveBayesWithID implements Serializable {

private NaiveBayes nb;
private static final long serialVersionUID = 1;
private static final int CURRENT_SERIAL_VERSION = 1;

public NaiveBayesWithID(NaiveBayes nb) {
this.nb = nb;
}
public NaiveBayesWithID(){
this.nb = null;
}

public void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
int version = in.readInt();
if (version != CURRENT_SERIAL_VERSION)
throw new ClassNotFoundException("Mismatched NaiveBayesTrainer versions: wanted " +
CURRENT_SERIAL_VERSION + ", got " +
version);

//default selections for the kind of Estimator used

NaiveBayesWithID test = (NaiveBayesWithID) in.readObject();
// nb = test.returnNB();
}

public void writeObject(ObjectOutputStream out) throws IOException
{
out.writeInt(CURRENT_SERIAL_VERSION);

//default selections for the kind of Estimator used
out.writeObject(this);
}

public NaiveBayes returnNB(){
return nb;
}

public void setNB(NaiveBayes nb){
this.nb = nb;
}

}


and here is the stack trace:

java.io.StreamCorruptedException: invalid type code: 00
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1355)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
at java.util.ArrayList.readObject(ArrayList.java:593)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1848)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
at cc.mallet.pipe.SerialPipes.readObject(SerialPipes.java:142)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:974)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1848)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
at guts.NaiveBayesWithID.readObject(NaiveBayesWithID.java:29)
at controllers.Application.predict(Application.java:481)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at play.mvc.ActionInvoker.invokeControllerMethod(ActionInvoker.java:408)
at play.mvc.ActionInvoker.invokeControllerMethod(ActionInvoker.java:403)
at play.mvc.ActionInvoker.invoke(ActionInvoker.java:176)
at play.server.PlayHandler$NettyInvocation.execute(PlayHandler.java:169)
at play.Invoker$Invocation.run(Invoker.java:187)
at play.server.PlayHandler$NettyInvocation.run(PlayHandler.java:149)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:206)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:680)


Does anyone know how I can get more information on the error? Or which object java is expecting?

Answer

You have implemented a recursive writeObject method: when you write an instance to an output stream, it calls the writeObject method, which writes an int, and then writes the object to the output stream, which write an int, etc.

The goal of the serialVersionUID field is to check that the objects are compatible. It's done natively by the serialization mechanism. You don't have to do anything except changing the serialVersionUID value when the class changes.