Linux and Java

 https://introcs.cs.princeton.edu/java/linux/

https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-on-ubuntu-18-04

https://ubuntu.com/tutorials/install-jre#1-overview

https://help.ubuntu.com/community/Java

https://www.java.com/en/download/help/linux_x64_install.html

https://www.guru99.com/how-to-install-java-on-ubuntu.html

C# TIPS:

https://www.monodevelop.com/documentation/stetic-gui-designer/