With Java 9, the entire Java platform, with every class in it, has been segregated and grouped into modules. Yes, all of the platform Java classes from Collections and Thread to Connection and Logger! It doesn't really matter which one; every platform class is now housed in newly created Java modules that come out-of-the-box with the runtime and the JDK. The platform team achieved this by going through both the public APIs and internal classes, grouping them based on the types that usually go well together and are self-contained, and bundling such related classes into modules.

Take Java logging for example. The native logging functionality in Java comprised of a group of classes in the package java.util.logging. These classes have now been grouped into a newly created module called java.logging. The JDBC and SQL related classes have all gone into a new...