How could we made a jar file's installer, which can run on multi-platform. Is there any simple way, because I don't know Java much well.
Balwant
Installer tools for Java have been dealt with in quite many questions on SO, and most options have probably been mentioned already:
See also other questions tagged java+installer.
If a commercial tool is ok, the best multi-platform installer for Java software, to my knowledge, is install4j; I can definitely recommend it (more about my experiences with it).