Tracking a feature through previews

Java 23 Course · lesson 12 of 15 · 4 min read

Structured concurrency and scoped values each hit their 3rd preview here - read the signal.

Open this lesson in the learning hub

Key points

  • A JEP that re-previews unchanged is stabilising; one that re-previews with API changes is still moving.
  • Structured concurrency reached its 3rd preview in 23 and its API kept shifting between releases.
  • Scoped values also reached a 3rd preview, but with a much more settled shape - and went final in 25.
  • The count alone is not the signal - read whether the API changed between previews.
  • Practical rule: adopt at final, experiment at preview, and never let preview code reach a release branch.

Judge a preview by whether its API changed since the last one, not by how many previews it has had.

Flexible constructor bodies (2nd preview) The Vector API and long incubations

This is a reading copy. The full lesson — with the visual explainer, the interactive lab and a Run button for the code — lives in the Java 23 Course course, and every lesson in it is listed on the Java 23 Course contents page.