XMLEncoder java version

Using xml: XMLEncoder java version on newest questions tagged xml – Stack Overflow

I use XMLEncoder to encode JGraph object to XML format. I use 2 machines to test, both of them have same java version as I check by cmd java -version

java version "1.6.0_27"
Java(TM) SE Runtime Environment (build 1.6.0_27-b07)
Java HotSpot(TM) 64-Bit Server VM (build 20.2-b06, mixed mode)

However, I get these XML headers from 2 machines as following:
Machine 1:

<java version="1.6.0_31" class="java.beans.XMLDecoder">

Machine 2:

<java version="1.7.0_05" class="java.beans.XMLDecoder">

Anyone knows why the java version is different?
The reason I ask this question because I suspect is the root cause for my following problem.
After that, I use XMLDecoder to decode the JGraph object. However, the graphModel gives me different result for

Object[] objs = graphModel.getOutgoingEdges(graphModel, cell);

With machine 1, objs has length = 1, machine 2 objs has length = 0.
Anyone has any idea? Is it the problem with java version?

source: http://stackoverflow.com/questions/11304482/xmlencoder-java-version
Using xml: using-xml