Android WiFi connectivity app — 2

I want a sample app in which both apps can communicate with each other using WiFi Direct or WiFi Hotspot (i.e. both devices can be connected to same WiFi network or connected to each other by sharing WiFi connection)
App must be able to detect when other device is connected and disconnected
Apps must be able to send text message or files to each other
(Note: I need complete source code and not the app)
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