Bump the minimum Java version?

[FDelporte]

At this moment, Pi4J V2 is built with Java 11 as the target, see https://github.com/Pi4J/pi4j-v2/blob/develop/pom.xml#L252

        <!-- JAVA COMPILER VERSIONS -->
        <java.version>11</java.version>
        <maven.compiler.source>${java.version}</maven.compiler.source>
        <maven.compiler.target>${java.version}</maven.compiler.target>

This means we miss out on many newer Java language and runtime improvements. Future versions will also make it easier to call C code to interact with the GPIOs, like JEP 454: Foreign Function & Memory API.

Do you agree we should move forward and bump Pi4J to a higher Java version? If so, which one?

[johanvos]

Is following the Tip & Tail approach (https://openjdk.org/jeps/14) an option here? You can branch out 11 here, and only add things to it when there are critical (security) issues, while using a later JDK version (21/23) on the tip?

[FDelporte]

Thanks for the tip! Will take a look at this...

[eitch]

Basically i have no issue back porting fixes. Lately most changes were new features and thus wouldn't have been backported anyhow. But the idea is definitely valid and i would always backport them, if needed.

[taartspi]

I selected the LTS. As the code base is used in various projects/products i think we owe the community the level with the most stable support

[FDelporte]

Last weeks I have been experimenting a bit with Java on 32-bit Raspberry Pi (for older boards). As far as I know, only Java 8 and 11 are available. So if we bump to a higher version, we will exclude these boards from newer Pi4J features later.

This is not a deal-breaker as we still will have the latest stable 2.X.Y release for those use-cases. But in that case, we will need to clearly document this.

[taartspi]

I saw u made v3.0 for the java 21. That works well for the users. We need to also add some doc detail on how we implement fixes needed in both versions.

[FDelporte]

It's only a first step, as an experiment to see if build etc. works... If we proceed like this, fixes will only applied in new V3 versions. Except for critical/security issues, these would be "backported".

[FDelporte]

Closing this discussion. As of version 3.0.0 Pi4J will be based on Java 21.

[laluha]

Keep java 11. ARMv6 devices has no java version higher than 11. This will abandon older pi's.

[FDelporte]

Agree and disagree ;-)
We have the stable version 2.8.0 which is Java 11 and is "feature complete" for all boards we know of today.
New development is mainly focused on newer boards like the new provider for Raspberry Pi 5 that was added recently.
Of course, critical bugs can still be backported to the 2-branch via the Tip & Tail approach described above by @johanvos

[FDelporte]

Java 21 branch is merged! See https://www.pi4j.com/blog/2025/20250211-welcome-java-21/