I have written a Java app and an NSIS installer. Works great. The issue is when there is a new version, the full installer needs to be downloaded and run (and possibly the old version uninstalled first).
How do you achieve the "Help >> Check for updates" system that Chrome, Firefox, dozens of other applications use to make staying current less painful.
Any guidance as to the direction to take would be appreciated.
Thanks.
Your question does not explicitly state that you want to stick with NSIS. So I take the chance to bring your attention to Java Web Start which requires relatively little setup work and allows to distribute updates without much hassle (and no user interaction required).
NSIS does not support updating as it seems, and trying to implement it in Java will lead to a portability nightmare. Web Start seems to be "just the right tool".
You can use the VPatch nsis plugin (part of the default install) to generate patches so you don't have to do a full install.