1 Getting Started

The guide highlights the significant changes and enhancements done in JDK 21.

This guide contains the following sections:

• Significant Changes in the JDK

• Security Updates

• Removed APIs

• Removed Tools and Components

• Preparing For Migration

• Migrating From JDK 8 to Later JDK Releases

• Next Steps

Note:

• Check the Oracle JDK Certified System Configurations page for the latest supported platforms and operating system versions.
• See Removed APIs, Tools, and Components before you start the migration process.
• See Be Aware Of The Default Charset if you are upgrading to JDK 17 or later.