Re: [Jung-support] ClassCastException that I can't figure out

[Joshua O'M. <jm...@ic...>]

On Tuesday, Oct 21, 2003, at 08:19 US/Pacific, cpb...@em... 
wrote:

> I am stumped (not SO surprising as I have been learning Java only for 
> the past several months). I cannot figure out WHY I keep getting the 
> exception in the following code:
> 				
> THE PROBLEM IS HERE-->	Edge up = GraphUtils.addEdge(g, 
> id.getVertex(i), id.getVertex(upI));
> 				Edge dn = GraphUtils.addEdge(g, id.getVertex(i), 
> id.getVertex(downI));
> 				
> The methods upIndex & downIndex return integers, the indexer selectes 
> the correct vertices using those integers and GraphUtils.addEdge 
> requires the arguments (graph, Archetypevertex, Archetypevertex) and 
> returns an AbstractSparseEdge. I have tried to initialize up and down 
> as AbstractSparseEdge and no luck. What am I doing wrong??

GraphUtils.addVertices(g, nodes) adds directed vertices to the graph, 
but g is undirected.  This should cause addVertices to throw an 
exception, but the current release of the code does not check for this 
incompatibility.  Instead, it appears that the incompatibility is 
encountered inside the call to GraphUtils.addEdge(), which is 
admittedly very confusing.

Use GraphUtils.addUndirectedVertices(g, nodes) instead.  This should 
fix your problem.  If not, please let us know and we'll help you figure 
it out.

For future reference, having the stack trace (the text that is printed 
when the exception is thrown) would be very helpful in tracking down 
errors like this.

We appreciate your interest in JUNG.

Regards,

Joshua O'Madadhain

  jm...@ic......Obscurium Per 
Obscurius...www.ics.uci.edu/~jmadden
   Joshua O'Madadhain: Information Scientist, Musician, 
Philosopher-At-Tall
  It's that moment of dawning comprehension that I live for--Bill 
Watterson
My opinions are too rational and insightful to be those of any 
organization.