Which language is used for developing solo learn

Answer 1

I'm using Android, so I can tell you it's Java. XML will most likely be present and various server side languages.

Answer 2

java, xml, html "and may be c++, java, php, sql on server side"

Answer 3

Java maybe?

Answer 4

for sure Java and objective-c are there since its mobile native application.
but it can be developed with Xamarin c#