I'd like to do some development of smart phone apps and my native programming language is java.
The first application I'd like to write will need to be able to (attempt to) connect to a network (LAN or WiFi) automatically in the background (on a schedule).
would an android phone be the best path or are there competitive purer java options?
I would definitely go with Android, extensive SDK, community, and increasing popularity. I think the What is Android answer on the developer web site says it all.
"Android is a software stack for mobile devices that includes an operating system, middleware and key applications. The Android SDK provides the tools and APIs necessary to begin developing applications on the Android platform using the Java programming language."