Android app server

Question

I want to create a simple chat application for Android.
I can make a Java application communicate with SQL database but I have no idea how to make 2 smart phones communicate with each other?
How to set up a server for an android application?
Can I make it for free?

Answer 1

Your lookit from the wrong side you don't have to make them communicate with each other you have to communicate with the sever and asking for messages.
If you just want to make them sql related make a table for new messages and a table for old messages and the Android app just have to "move the messages"
(Deleting them from the new table and recreting the them in the old table)
Now tho your second question. No you'll still need a server with a stable ip or just a stable ip and a server (for small scale a raspery pi should do it) at home

Answer 2

look into coding sockets and server connections.

Answer 3

Ohh yeah for lage scale with public access write something server sided that's secure to ensure an sql injection is not possible