I have modified install locations:

• .so files are in /usr/lib/java-openjfx
• .jar and .jmod files are in /usr/share/java/java-openjfx

Some variables are defined in /etc/profile.d/java-openjfx-profile.sh. /usr/bin/java-openjfx-env can also be sourced. To launch an application with openjfx, you can use for example:

source java-openjfx-env
java $OPENJFX_JAVA_OPTIONS --add-modules javafx.swing,... <your java application>

What java are you using? I'm building with jdk25-openjdk.

...
FAILURE: Build failed with an exception.

* What went wrong:
BUG! exception in phase 'semantic analysis' in source unit '_BuildScript_' Unsupported class file major version 70
> Unsupported class file major version 70

I updated the version requirement to >= 25.

I'm hesitant to bump java to 26 when version 25 is still in repos (jdk25-openjdk) and upstream is still building with version 25. You can still use openjfx with java 26 after it's built.

Java 26 is what is in the repo now. Could you update?

Could you change _java_ver=25 please ? V25 is what is in repos now. Building V24 to install FX for V25 is a bit overkill. I try that locally, it builds. Oh, and replace "gradle8" with just "gradle".

==> Starting build()...
To honour the JVM settings for this build a single-use Daemon process will be forked. For more on this, please refer to https://docs.gradle.org/8.14.3/userguide/gradle_daemon.html#sec:disabling_the_daemon in the Gradle documentation.
Daemon will be stopped at the end of the build 
> Task :buildSrc:compileGroovy FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':buildSrc:compileGroovy'.
> BUG! exception in phase 'semantic analysis' in source unit '/home/user/.cache/yay/java-openjfx/src/jfx-26-15/buildSrc/src/main/groovy/com/sun/javafx/gradle/CCTask.groovy' Unsupported class file major version 69

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

BUILD FAILED in 20s
1 actionable task: 1 executed
==> ERROR: A failure occurred in build().
    Aborting...
 -> error making: java-openjfx-exit status 4

Need to add file like /etc/profile.d/java-global-options.sh

With content

!/bin/sh

Set global Java options to include the JavaFX native library path

export _JAVA_OPTIONS="-Djava.library.path=/usr/lib/java-openjfx"