If designed properly Java application can be fast and attractive.
Popular belief is all Java apps are slow and ugly, but with little effort they can be made attractive too.
Just have a look on XDM 2015 Linux/OS X version
i. Browser Integration:
Most of the other download managers uses browser plugins (extensions to be more accurate) to integrate with the browser.
The extension gets installed on the browser and uses browsers api to monitor and capture downloads.
a. For each browser need an extension written for it.
b. Whenever a new version of the browser is released with major changes the extension may become incompatible with the browser.
c. Download managers can provide extensions for only a handful popular browsers only.... read more