Hi, this article is a about setting up a XMPP chat using latest smack library in android.
Before starting the coding part lets start with smack library
http://www.igniterealtime.org/projects/smack/. A pure Java library, it can be embedded into your applications to create anything from a full XMPP client to simple XMPP integrations such as sending notification messages and presence-enabling devices. Smack and XMPP allows you to easily exchange data, in various ways e.g. fire-and-forget, publish-subscribe, between human and non-human endpoints.
You can find more about About smack github, the latest smack is made much compatible with android.Old release was meant for web based type chat system it was not handling the conditions like deep sleep mode,timeout in mobile also connectivity issue etc, all but is handling in the latest version, to find more about smack deeply just go though this documentation
Some of the xmpp Servers you can work with
Some of the Useful Android Projects