If you really want to go to the JavaCard programming level, current NetBeans http://www.netbeans.org/ (6.9.1 and later) have a JavaCard module that comes with a JC3 card emulator, allowing you to test your cards / applets by simply clicking run (or debug) in a JavaCard project.
This is pretty convenient, but beware of different versions of JavaCard and check which features, functions and parameters are really available for the version of the platform for which you are programming at the end.
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