I have worked on java in android as well as with html, css integration with android. Also I did programming on camera integration, sms receive,processing and sending, location services, working with realm (local database android), used volley to send data to APIs over http request etc, making persistent app by storing data in shared preferences, login environments on google or other server, bank menu layouts, fragments, and other ui layouts, etc. I am currently going through the material design and have learnt many stuff in that too.