the current implementations in the class Visit (package org.apache.commons.graph.visit) do not include the possibility to stop the search prematurely. That would be more natural (and faster) for many kinds of search, e.g. when looking for the first occurrence of a specific pattern (vertex, path with certain features, etc).
The easiest solution: changing all method signatures in GraphVisitHandler from void to boolean, forcing the handler to answer the question: should I continue?
I understand semantics get a bit entangled (well, not with an appropriate documentation!), so I am open to more verbose options: e.g. a method isSearchComplete to call after every step... but that would only be more verbose, wouldn't it?
Waiting for feedback and ready to patch