network awareness with help of NM in Java/C/C++

["Syed Md. Ashraful Karim" <ashraful ansur no>]

Hi All,
I want to make an application that respond to the change of mobile
networks (Ethernet, wireless, 3g, satellite) changes. For that I need to
sense any changes in the network, the way NetworkManager do. 

Its like, I want to catch any event in Java/C++ code, when any changes
occurred in the network interfaces up/down. 

Can anybody tell me, how can I do that? Any library in NM or HAL? A
sample code or hints is very much appreciable.

Thanks in advance.

/Ashraf