With the release of Java 9 and later versions, the traditional rt.jar file has been replaced by the Java Platform Module System (JPMS), also known as Project Jigsaw. This new system modularizes the Java runtime, making it more scalable and maintainable. In these versions, core classes are divided into modules rather than being bundled in a single rt.jar file.

If you’re using Java 9 or later, you won’t find rt.jar, and instead, you’ll encounter the module system that provides a more granular way of organizing and loading Java classes.