Java Portable Apps Packaged as Exe

Hello, I stumbled some apps like this one in the past. The big question is, is it possible to run them via Java Portable Launcher. So far I have been unable to do so. To name some portable java apps packaged as executables: DocFetcher, TVBrowser (which is I recap correctly is hosted in Sourceforge, hence opensource?)

I recently knew of JAR2EXE Converter, which makes my wonder the advantages of converting to exe and if this may become a trend. Maybe I'm outtalking...since I havent tested the converted exes in this case, It can be that the converted executables dont requiere java since as per the website explanation states it has been used for converting small nokia games..
Anyway the question and what gets my interest more is whether is possible to run portable java apps with an executable using JPL.