Re: get a list of classes at runtime

Posted by Joerg... on 13. May 2015

On Wed, 13 May 2015 14:47:40 +0200, Philipp Kraus wrote:




I would like to get a list of all loadable classes, because I create an
UI which should be list on the user input, which classes are existst
e.g. the user types ABC and I will get the full class name with
packages, e.g. package1.subpackage.ABC and package2.ABC




What you want is not quite possible. Since class loaders load on demand
(and some even from remote sources over the internet or out of a database),
there is no list of "possible loadable classes". You could write a loop
that attempts to load "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab" and so on, but that is unlikely to
produce an outcome you will be happy with.



Your question is akin to saying "I would like a list of all available
URLs". It just doesn't work like that.



There are of course many ways to get all loaded classes, but that again is
probably not what you want. Your best bet is something that scans all the
jars on the classpath, which will not give you an exhaustive list, but a
reasonable approximation.



This library may be helpful: https://code.google.com/p/reflections/



Spring also has something helpful:
http://static.springsource.org/spring/docs/2.5.x/api/org/springframework/context/annotation/ClassPathScanningCandidateComponentProvider.html



Good luck.



Liebe Gruesse,
Joerg





Ich lese meine Emails nicht, replies to Email bleiben also leider
ungelesen.


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