The `System.getProperty("java.home")` points to the JRE bundled with Processing and not the JDK

[pervisjohannsen]

Most appropriate sub-area of Processing 4?

Core/Environment/Rendering

Processing version

4.4.0 through 4.4.4

Operating system

Linux Fedora/KDE, Windows 11, and MacOS X Sonoma (intel)

Bug description

I’m getting these errors with code that worked in version 4.3.4,

The package “java.sql” does not exist. You might be missing a library.
The package “com.sun.net” does not exist. You might be missing a library.

Steps to reproduce this

"1.Run a sketch that imports these packages.

"

snippet

// Paste your code below :)
import java.sql.*;
import com.sun.net.httpserver.*;

void setup() {

}

void draw() {

}

Additional context

I've tested version 4.4.4 and previous versions back to 4.4.0 on Linux/MacOS/Windows and all exhibit this bug.
I am selecting that I'd like to help but I have no experience in Gradle, etc.

Would you like to work on the issue?

Yes, I’d like to help with this

[SableRaf]

Thanks @pervisjohannsen for reporting this and testing on different versions.

Processing 4.4 switched from bundling a full JDK to generating a custom JRE with jlink as part of the new Gradle build (see #888, #968, and the 4.4 release notes). To reduce the download size, only a minimal set of modules was included.

I tested a fix locally by adding java.sql to the modules list in nativeDistributions inside of app/build.gradle.kts (same place where java.scripting was added in PR #1056). After rebuilding, the sketch compiles and runs fine again (see screenshot below). I also tried adding jdk.httpserver but the sketch still shows No library found for com.sun.net.httpserver 🤔 That's as far as I was able to get with my limited knowledge of Gradle.

We could include these in the build, but this raises a broader question about which modules we should include by default. We're currently migrating the internal sketch runner to Gradle, and I'm guessing that could eventually support automatically resolving or downloading missing modules (@Stefterv let me know if I’m on the right track here).

[Stefterv]

Hmm, I am surprised that did anything to be honest. We include the entire JDK for building sketches so there should not be any missing modules. At #1056 there was a missing module for code that ran within the PDE, so that is a different case than here. I suspect somehow the compilation stage is using the wrong JDK?

[SableRaf]

Ok I edited my comment to cross out my wrong assumptions :D

[pervisjohannsen]

This may be irrelevant now, but I think jdk.httpserver is just a wrapper for com.sun.net.httpserver.

[Stefterv]

Just ran the debugger and the Eclipse Compiler is hardcoded to use the System.getProperty("java.home") so we can temporarily override the system property before running the old compiler, or another solution if anyone has better ideas.

[Stefterv]

This solves the issue with java.sql not being available, not sure if setting System.getProperty("java.home") is going wreck havoc somewhere else so not a fan of this solution.

[Stefterv]

https://discourse.processing.org/t/javadoc-doesnt-work-anymore-processing-on-linux/46868

I just took a look through the code in this repo and it also relies on java.home property

[Stefterv]

Also seems to be related to ongoing the Android mode issues: https://discourse.processing.org/t/android-programming-for-beginners/46813/13