Implementation of GUI

Question

When you check Wikipedia about some softwares you see things like "written in C or Java or C# etc" but how actually are graphics added to these programs? because many book only teach these programming languages tutorials with Clients.

Answer 1

For Java see these tutorials:
http://docs.oracle.com/javase/8/javase-clienttechnologies.htm

Answer 2

Thanks a lot @Tashi. Appreciated!