More than a language, Java is a platform that was developed for Sun. Its most important feature is that it is multi-platform.
The Java generator allows generating web applications. The programs generated are Java code sources (.java), compiled into classes (.class) that may be run on any platform with a Java virtual machine and Servlets Server for interpreting them.
The applications communicate with the database through JDBC drivers, and the available DBMS are all those supported by GeneXus: DB2 UDB for iSeries, DB2 Universal Database, Informix, MySQL, Oracle, PostgreSQL and SQL Server or other Cloud Databases.
Check GeneXus 18 hardware and software requirements and Java Generator Requirements.
To deploy Java applications, use the Application Deployment tool