J2HTML (j2html) is a Java library used to generate HTML I have been using it to create Web 1.0 applications in Java. Web 1.0 is server-side rendering pages with minimal Javascript. As I got deeper into using the library I started to read the actual source code of this library with an eye on following Java best practices and to my pleasant surprise, this code follows many of them. I am going to show here some examples of using interesting Java features, beyond the basics. 1. Functional Interface People are aware that Java supports some form of Functional Programming, and here is an example of using it: @FunctionalInterface public interface Indenter { String indent( int level , String text ); } public static Indenter indenter = ( level , text ) -> String. join ( "" , Collections. nCopies ( level , FOUR_SPACES )) + text ; Things that I noticed: String has a method called join. I used before StringUtils.join, but now that is in the standard library I don’t need to us