Re: [jgrapht-users] Documentation, implementation or me?

[Jonathan C. <jon...@it...>]

Exactly what I thought. But... is this really what a graph should be? I mean, there is no hint in the docs as far as I can see, and although I know it is not good practice to change things in a collection from the outside, it still seems like something you might want to do. In particular if the graph represents some meta level info...

/J

On 16 nov 2010, at 03.18, John Sichi wrote:

> Hi Jonathan,
> 
> s2 is a mutable object, and you changed it after adding it to the
> graph.  That's why you got unexpected results.
> 
> See the section "Good keys" in this article:
> 
> http://www.ibm.com/developerworks/java/library/j-jtp02183.html
> 
> JVS
> 
> On Mon, Nov 15, 2010 at 5:23 PM, Jonathan Cederberg
> <jon...@it...> wrote:
>> I am a huge fan of jgrapht. However, I have come across a problem with it.
>> My understanding is that that the code below should work, but it doesn't. I
>> have not dug into the source, but I can imagine that there is a hashcode
>> issue, as it no longer seem to find the vertex that is there.
>> I am not sure if I have read the docs wrong, programmed wrong, or if this is
>> simply a bug. The latter seems unlikely though, since it is such a core
>> feature that this type of problem should have been caught long ago.
>> Thanks in advance for any help!
>> /Jonathan
>> 
>> import java.util.LinkedHashSet;
>> import java.util.Set;
>> import org.jgrapht.graph.DefaultEdge;
>> import org.jgrapht.graph.SimpleGraph;
>> public class Main {
>> /**
>> * @param args
>> */
>> public static void main(String[] args) {
>> SimpleGraph<Set<String>, DefaultEdge> sg =
>> new SimpleGraph<Set<String>, DefaultEdge>(DefaultEdge.class);
>> 
>> Set<String> s1, s2;
>> s2 = new LinkedHashSet<String>();
>> s2.add("y");
>> s2.add("z");
>> 
>> sg.addVertex(s2);
>> 
>> s2.remove("z");
>> 
>> // this is true, as expected
>> assert(sg.vertexSet().size()==1) : "There is no vertex any more.";
>> assert(sg.vertexSet().iterator().next()==s2) : "Not the same vertex!";
>> 
>> // but this is false!
>> assert(sg.containsVertex(s2)) : "The vertex is gone!";
>> }
>> }
>> 
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