More robust serialization mechanism needed - json serialization would be better in terms of robustness and performance

[gokhanercan]

Serialized object highly dependent on class types and hierarchies. NGram or similar java object serialization are sensitive to member changes of such class types. Library users should frequently update such serialized resource files on their implementations. If a serialized file "word2.gram" file was serialized by the previous version of the class NGram or Word, loading previous models would yields exceptions like the following:

java.io.InvalidClassException: Dictionary.Word; local class incompatible: stream classdesc serialVersionUID = 2071394599407976767, local class serialVersionUID = -2752853122563649172
at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:621)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1623)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1518)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1774)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
at java.util.HashMap.readObject(HashMap.java:1394)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1896)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
at MorphologicalDisambiguation.NaiveDisambiguation.loadModel(NaiveDisambiguation.java:32)
at MorphologicalDisambiguation.RootFirstDisambiguation.loadModel(RootFirstDisambiguation.java:187)

https://github.com/olcaytaner/MorphologicalDisambiguation/blob/master/src/main/java/MorphologicalDisambiguation/NaiveDisambiguation.java#L27

[gokhanercan]

For the records, everytime I face this issue, I regenerate the files with the following:

/*
Regenerates files words.1gram, words.2gram, igs.1gram, igs.2gram.
After executing, copy output files on the root to the resources folder of your implementation.
 */
public static void ReserializeGrams(){
    RootFirstDisambiguation disambiguation = new RootFirstDisambiguation();
    DisambiguationCorpus corpus = new DisambiguationCorpus("dataset/disambiguation/penn_treebank.txt");
    disambiguation.train(corpus);
    disambiguation.saveModel();
}