Dynamic loading of java class for activiti Service Task -

i need dynamically load jar , extract classes classpath, there no need of restarting server. activi service task, java class available jar. tried out below, @ point service task deployed gives error "cannot instantiate packagename.classname. " guess means class cannot found.

urlclassloader loader = (urlclassloader)classloader.getsystemclassloader();         log.info("loader" +loader.geturls());      myclassloader l = new myclassloader(loader.geturls());         l.addurl(new url("jar","","file:"+artifactlocation+"!/"));       jarfile jarfile = new jarfile(artifactlocation);     enumeration e = jarfile.entries();      while (e.hasmoreelements()) {          jarentry je = (jarentry) e.nextelement();          if (je.isdirectory() || !je.getname().endswith(".class")) {              continue;          }          // -6 because of .class           string classname = je.getname().substring(0, je.getname().length() - 6);          classname = classname.replace('/', '.');         class c = l.loadclass(classname); 

any idea on how solve custom classloader other osgi method?

• you cannot safely assume system classloader instance of urlclassloader. is, might not true next version of java.
• no need write own classloader, urlclassloader fine. , when instantiated urlclassloader(url[] urls) constructor, delegate parent classloader, need url of own .jar file(s).
• no need extract .class files, classloader knows how load classes .jar file
• you might want set custom classloader current - along thread.currentthread().setcontextclassloader(l)
• eventually, might load classes using class.forname("my.foo.class")