Chapter 5. Preparation for migration
Red Hat build of OpenJDK 21 includes changes that might require you to reconfigure your applications, which were already successfully deployed on Red Hat build of OpenJDK version 8, 11, or 17.
You can ensure an effective migration plan by completing the following tasks, as appropriate:
- If you currently use Red Hat build of OpenJDK 8, review the Major differences between Red Hat build of OpenJDK 8 and Red Hat build of OpenJDK 11 section to familiarize yourself with the changes that are available from version 11 onward.
- If you currently use Red Hat build of OpenJDK 11 or earlier, review the Major differences between Red Hat build of OpenJDK 11 and Red Hat build of OpenJDK 17 section to familiarize yourself with the changes that are available from version 17 onward.
- Review the Major differences between Red Hat build of OpenJDK 17 and Red Hat build of OpenJDK 21 section to familiarize yourself with the changes that are available from version 21 onward.
- Integrate the differences into your migration plan.
Red Hat provides a migration toolkit for applications (MTA) tool that you can use to help with your migration tasks. You can use the MTA tool to migrate Java applications from Red Hat build of OpenJDK version 8, 11, or 17 to Red Hat build of OpenJDK 21.
Additional resources
- For more information about the installation of Red Hat build of OpenJDK 21 on RHEL, see the Installing and using Red Hat build of OpenJDK 21 on RHEL guide.
- For more information about the installation of Red Hat build of OpenJDK 21 on Microsoft Windows, see the Installing and using Red Hat build of OpenJDK 21 for Windows guide.
- For more information about switching between Red Hat build of OpenJDK versions on RHEL, see Interactively selecting a system-wide Red Hat build of OpenJDK version on RHEL in the Configuring Red Hat build of OpenJDK 21 on RHEL guide.
- For more information about the MTA tool, see the Introduction to the Migration Toolkit for Applications guide.
