LibreOffice Base without Java
Good question!
As you might be aware, the default database backend for Base (used to store databases locally, in a single file) is HSQLDB, “a relational database management system written in Java.”
Base can, however, connect to a variety of different databases “including Access databases (JET), ODBC/JDBC data sources, and MySQL or PostgreSQL.”
The official system requirements page does say “Java is notably required for Base,” however it’s possible that this is merely a simplification, and that as long as you only use remote databases, Base can be run. Of course, at that point you’re off into uncharted territory, and (as the saying goes) if anything breaks, you get to keep both pieces 
The Official LibreOffice FAQ used to indicate that Base only required java for HSQLDB support, but that FAQ entry is gone, so I can’t provided any certainty that Base hasn’t picked up another java dependency.
This is a very relevant question, and one that has been posed by many people. There’s currently work underway to remove the java dependency from Base, so I can say with some confidence that eventually you will not need Java to run Base, however I’m not really sure when that change will come to pass!
Here are some related questions:
Base requires Java at least for :
- the embedded hsqldb 1.8 engine, which is the default for ODB files ;
- the integrated ReportBuilder extension, which is written in Java.
If you are not using any of those, then you might be able to get away without having to install a JVM/JDK.
In my case, the program asks me to install Java. I have no chance. I have no way to do not use Java. The program, simply, doesn’t work