How to serilaize nested classes

Need to create xml like from a java class.
<Top level class>
<member1>1</memeber1> //members of top level class
<member2>2</memeber2>//
<Sub class>--------------------------//
<member1>1</memeber1> // members of sub class
<member2>2</memeber2>
</Sub class>
</Top level class>

Can this type of xml be generated from a java object using XSTREAM ?

If this can be done then plz let me know the best way of doing it and HOW SHOULD i DECLARE MY JAVA CLASS.

public class TopLevelClass

public class SubClass{
private String member1;
private String member2;
}

Thx