Can't use latest Java Version (JDK 21) in IntelliJ IDEA

Question

I'm using macOS and I want to try Java 21 in IntelliJ IDEA. I believe I have done all the required steps to change Java version of a project / module. Nevertheless I still can't use new Java 21 Features, such as String Templates. How to be able to use Java 21 in IntelliJ?

I have changed:

• Project SDK to 21

• Module SDK to 21

• OS java version to 21. Typing java -version in terminal outputs:

  java version "21" 2023-09-19 LTS

  Java(TM) SE Runtime Environment (build 21+35-LTS-2513)

  Java HotSpot(TM) 64-Bit Server VM (build 21+35-LTS-2513, mixed mode, sharing)

• I have also updated IntelliJ to version 2023.2

Answer 1

I needed to update Intellij version to 2023.2.2 and change Language level (File -> Project structure -> project -> language level) to 21 (preview)

The new language level won't show up until Intellij is updated to the latest version.

To update Intellij, I needed to manually check for new update

Manually updating Intellij on Mac

Intellij IDEA | Check for Updates

Manually updating Intellij on Windows / Linux

File | Settings | Appearance & Behavior | System Settings | Updates