Java is an object-oriented programming language, that appeared in 
1995. The most recent version of the programming language is 
version 16\footnote{March 2021}. In order to write Java programs, 
one needs to install the so-called \emph{Java Development Kit 
(JDK)}.\footnote{\url{https://www.oracle.com/java/technologies/javase-downloads.html}}
Java programs can be written independently from the operating 
system that one uses.
