Intellij 2024.2: Investigation of Changes Needed to Support Java 21

[vaisakhkannan]

As part of supporting IntelliJ 2024.2, we need to support Java version 21. During the investigation, we found that our development environment should also run on the Java 21 SDK. Therefore, we need to update the Java version to 21 for the sample projects used in test automation.

[staicy123]

Hi @TrevCraw, this is where we found that the source compatibility for intellij version 2024.2 should be 21.

staicymathew@staicys-mbp liberty-tools-intellij2 % ./gradlew buildPlugin

Task :patchPluginXml
[org.jetbrains.intellij.platform] Patching plugin.xml: attribute 'since-build=[241]' of 'idea-version' tag will be set to '242.20224'
[org.jetbrains.intellij.platform] Patching plugin.xml: attribute 'until-build=[241.]' of 'idea-version' tag will be set to '242.'

Task :verifyPluginProjectConfiguration
[org.jetbrains.intellij.platform] The following plugin configuration issues were found:

• The IntelliJ Platform cache directory should be excluded from the version control system. Add the '.intellijPlatform' entry to the '.gitignore' file.
• The Java configuration specifies sourceCompatibility='17' but IntelliJ Platform '2024.2.0.1' requires sourceCompatibility='21'.

https://plugins.jetbrains.com/docs/intellij/build-number-ranges.html#platformVersions

[TrevCraw]

Regarding Java versions, as long as we are not using Java 21 features, we may be able to build against Java 21 and run on Java 17. Or, if that is not best practice, it may be possible to build with Java 17 and run on Java 21. I will defer to @mrglavas for the best way to achieve multiple levels of JVM support.

Regardless of the strategy, we will need to test it out. We should be able to find a way to support both 2024.1 and 2024.2. According to the JetBrains marketplace, Quarkus Tools supports both 2024.1 and 2024.2 - https://plugins.jetbrains.com/plugin/13234-quarkus-tools/versions. I do not see Quarkus Tools using Java 21 in their build file - https://github.com/redhat-developer/intellij-quarkus/blob/main/build.gradle.kts#L133-L139. I would recommend trying out Quarkus Tools on 2024.2.

Maybe you can find other example plugins that support 2024.1 and 2024.2 and see how they do it?

[TrevCraw]

Hi @mrglavas , I am not sure of the best practice regarding supporting multiple Java versions with one build, but I am wondering if it is even achievable based on how the IntelliJ ecosystem is set up.

[TrevCraw]

Hi @staicy123, @vaisakhkannan, after a discussion with @mrglavas and @turkeylurkey, it is recommended that we do not build with Java 21 and run on Java 17, as there are potential negative side effects. It should be safe, however, to build with Java 17 and run on Java 21. In order to do that, we need to do a few things:

• Our production build would need to be targeted to Java 17 and IntelliJ 2024.1.
• Confirm that a plugin built with Java 17 and IntelliJ 2024.1 can run on IntelliJ 2024.2.
• Development work needs to be completed using Java 21 and IntelliJ 2024.2 to find any issues and deal with any methods that may have been removed between 2024.1 and 2024.2.
• Reach out to JetBrains to inform them of how we plan to support 2024.1 and 2024.2 to see if our strategy is reasonable and ask if there is a better or recommended way to support both 2024.1 and 2024.2.

[staicy123]

Hi @TrevCraw, please find the discussion with jetbrains team regarding using java 17 here https://jetbrains-platform.slack.com/archives/C5U8BM1MK/p1729162829013169

[vaisakhkannan]

Hi @TrevCraw, I checked the Quarkus Tools plugin code, cloned it, and ran the extension and UI tests. I found that both the extension IDE and UI test IDE are running on IntelliJ version 2023.2, but they also support IntelliJ 2024.2. I was able to install the Quarkus Tools plugin in IntelliJ 2024.2.

The reason they did not specify the untilBuild is that it indicates support for every latest release. They may be testing the plugin using EAP IntelliJ versions.

[staicy123]

Our intention is to support both IntelliJ 2024.1 and 2024.2, so we have decided to set the common Java version to 17. However, we have also verified that we can support Java version 21 in IntelliJ 2024.2. Therefore, we will be closing this issue.