I need resources on how to analyze a java object programatically and
from that create a UML diagram with aggregation, inheritance,
interface, dependency relationships etc.

What UML editors can do this and which of them are free/trial
download?

Tutorials, online books and documents, anything that touches the issue
in depth specifically for the java language.

In java, reflection is of course used to do the analysis and I expect
resources to be substantial in covering reflection.

Example:
java.lang.String object is to be analyzed. 
Which are its superclasses?
Which interfaces does it implement?
Which objects is it dependent upon?
Which objects does it aggregate?

Any great resouce on the subject would cover this.

Here are some Programs that enable you to generate UML from Java code
:

 - University of Paderborn : FUJABA ( From Uml to Java And Back Again
)
  ( http://www.upb.de/cs/ag-schaefer/Lehre/PG/Fujaba/fujaba.html )
   Free(GPL). Written in Java
  "FUJABA combines UML class diagrams, UML behaviour diagrams, SDM
story diagrams, and design patterns to a powerful, easy to use, yet
formal system design and specification language."

 - Visual Paradigm for UML
   ( http://www.visual-paradigm.com/vpuml.php )
    Commercial. Free Community Edition Available.

 - Poseidon for UML 
   ( http://www.gentleware.com/ )
   Commercial $699. Free Community Edition available.
   Based on the open source ArgoUML ( argouml.tigris.org ) tool.

 - Rational® XDE™ Professional v2002: Java™ Platform Edition
   ( http://www.rational.com/products/xde/javaed/index.jsp )
   Commercial $3595. Free Evaluation available.
   Combines design and development into a single Java Integrated
Development Environment. Converts Java code to UML as you type.Works
with all leading Java IDE's.
 
 - SilverRun's Java Designer Kit
   ( http://www.silverrun.com/jd.html )
   Commercial $189. Free demo available.
   A UML-based modeling tool for designing, forward and reverse
engineering Java applications and applets.

You can also find other such UML tools at :
   - Objects By Design
    ( http://www.objectsbydesign.com/tools/umltools_byCompany.html )
    Look for products that support Round trip engineering.

  
====

This topic, generation UML from Java code has been a subject of the
following papers/thesis. These should provide you with ample
information.

 - Design Pattern Extraction for Software Documentation
   Author: Osvaldo Pinali Doederlein 
   ( http://www.geocities.com/ResearchTriangle/Node/2005/thesis.htm )

 - Recovering UML Diagrams from Java Code using Patterns
   Authors : J. Niere, J.P. Wadsack, A. Zündorf
   ( http://gwydion.upb.de:8080/servlet/PaperReader )

 - Utility Support for Checking OCL Business : Rules in Java Programs
   Author : Ralf Wiebicke 
   ( http://rw7.de/ralf/index.en.html)

You can also find articles on Java/UML code generation at
 - Software reality : Automated Code Generation 
   ( http://www.softwarereality.com/programming/code_generation7.jsp )

A list of Java Reflection Tutorials can be found at :
  - TutorGig.com - Reflection
    ( http://www.tutorgig.com/showurls.jsp?group=2564&index=0 )

Hope this helped.
If you need any clarifications, just ask!
:)

Probably the best tool is TogetherSoft's 'Control Center' - 

http://www.togethersoft.com/products/controlcenter/index.jsp

Another to try is ArgoUML - 

http://argouml.tigris.org/

pemo