Serialize superclass(es) before subclasses - boolean configuration property

Java serialization always serializing superclasses before subclasses:

http://www.oreilly.com/catalog/javarmi/chapter/ch10.html

"An important part of serialization involves writing out class-related metadata associated with an instance. Most instances are more than one class. For example, an instance of String is also an instance of Object. Any given instance, however, is an instance of only a few classes. These classes can be written as a sequence: C1, C2...CN, in which C1 is a superclass of C2, C2 is a superclass of C3, and so on. This is actually a linear sequence because Java is a single inheritance language for classes. We call C1 the least superclass and CN the most-derived class."

Hi Geoffrey,

the latest SNAPSHOT version has already a FieldKeySorter interface. I've checked in now an implementation, that works as suggested. You give it a try. See the CustomFieldKeySorter acceptance test how XStream can be initialized with such a sorter and make use of the NativeFieldKeySorter implementation. Report back, if it works for you.

• Jörg

I 'll try it out.
1.3.0 will use this by default right?

Yes, 1.3.x will do this by default.

It works for me with:
xStream = new XStream(new PureJavaReflectionProvider(new FieldDictionary(new NativeFieldKeySorter())));

Great work

Note that 1.4.1 still uses ImmutableFieldKeySorter by default:

	public PureJavaReflectionProvider() {
		this(new FieldDictionary(new ImmutableFieldKeySorter()));
	}

With 1.4.3, I am able to use

xstream = new XStream()

and not run into this issue apparently.

This was also the case with older versions. See, what we changed with 1.3.x was the algorithm to collect the fields. Therefore we could use then ImmutableFieldKeySorter (because the fields were already sorted in declaration order) while for older XStream versions you actually had to sort them ti get this native order.