JDK 19: Constant class entries ending in '/' - Quality Outreach Heads-up

by David Delabassee on February 10, 2022

The OpenJDK Quality Group promotes the testing of FOSS projects with OpenJDK early-access builds as a way to improve the overall quality of the release. This heads-up is part of a Quality Outreach update sent to the projects involved. To learn more about the program and how to join, please check the Quality Outreach wiki page.

JDK 19: Constant class entries ending in '/'

Prior to JDK 19, the JVM is loading classes (1) whose class file major version is <49, i.e., before JDK 1.5, and (2) the class's name ends with a '/'. This violates section 4.2.1 of the JVM specification and is addressed in JDK 19. In JDK 19, the JVM is throwing, for such classes, a ClassFormatError exception as it already does with newer classes (JDK 1.5+). Given that this issue affects only pre-JDK 1.5 classes, the compatibility risk is expected to be very low.

Call to Action

No action is required unless codebase using pre-JDK 1.5 classes are involved. Questions and proper feedback should be sent to the hotspot-dev mailing list.