B4J Question [SOLVED]Java 21 Environment

[bdunkleysmith]

I believe I've downloaded "the three pieces and put them in the right place" to create a Java 21 environment as per this post by @Erel in order to confirm updating from Java 19 to Java 21 doesn't eliminate a problem I'm encountering with an app, but something's not quite right.

Firstly when I compile the app, it says Java Version: 8 as per below, whereas under Java 19 indeed it says Java Version: 19:

Does this indicate the contents and/or structure of the "three pieces" is wrong?

After compilation the app runs and my log suggests it's running in a Java 19 environment, but when I click on a button to load a video into MediaView, the following fatal error is thrown:

BDSSynergyPlayerBoard V21 - Ringwood started at 16/5/2025 23:15:18
Java version: 21.0.7
Host Address: 192.168.0.22
main._btnloadvideo_click (java line: 2337)
java.lang.ClassCastException: class java.lang.UnsatisfiedLinkError cannot be cast to class java.lang.Exception (java.lang.UnsatisfiedLinkError and java.lang.Exception are in module java.base of loader 'bootstrap')
at anywheresoftware.b4a.BA.setLastException(BA.java:399)
at b4j.example.main._btnloadvideo_click(main.java:2337)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:111)
at anywheresoftware.b4a.BA$1.run(BA.java:236)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:456)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:455)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
at java.base/java.lang.Thread.run(Thread.java:1583)

Any guidance would be appreciated or ideally if someone has a complete zip of the "three pieces" for a functional Java 21 environment, I'd appreciate a link to it.

 

[aeric]

Try read this thread:

OpenJDK 17 or 19? JavaFX SDK 17?

I understand that the recommended version for B4J (current version 9.80) is OpenJDK 11. Should I combine javafx17 with openjdk17? Or can I leave open jdk11? Better to use jdk11 or 14. https://www.b4x.com/android/forum/threads/update-openjdk.140167/ Note that you can use any version of...

www.b4x.com

 

[aeric]

Click on menu Tools -> Configure Paths
Make sure you are setting the correct path.

 

[bdunkleysmith]

Thanks @aeric, but everything's working fine for Java 19.0.2. I am trying to create a Java 21 environment and there appears to be many sources for the various components and depending on the source, I either have the errors noted above or even this one where I can't even compile the app

As I said above, why does it say Java Version: 8 even though I've pointed to javac.exe in the Java21 folder structure:

I downloaded openjdk-21_windows-x64_bin.zip, the 21 GA (build 21+35) from https://jdk.java.net/archive/ then openjfx-21.0.7_windows-x64_bin-sdk.zip and openjfx-21.0.7_windows-x64_bin-jmods.zip from https://gluonhq.com/products/javafx/, and arranged them in the folder structure specified in the other post I referenced.

I assume the javafx and javafx-mods files are not compatible with the openjdk file.

It would be nice just to be able to download a single zip for a Java 21 package just like the link on the B4J product page allows download of the Java 19 one.

 

[aeric]

Add this line:

#JavaCompilerPath: 21, C:/Java/jdk-21.0.7/bin/javac.exe

source: https://www.b4x.com/android/forum/threads/openjdk-17-or-19-javafx-sdk-17.145853/page-2#post-972329

 

[teddybear]

You need to add the #JavaCompilerPath:21, javacpath(java21) in Main.

 

[bdunkleysmith]

Thank you @aeric and @teddybear.

Indeed adding

#JavaCompilerPath: 21, C:/Java/jdk-21.0.7/bin/javac.exe

results in Java Version: 21 being shown and the app compiling/running without error.

My understanding was that adding #JavaCompilerPath just overrode the path selected in the Paths Configuration dialog box, however it seems for at least Java 21, explicit definition using #JavaCompilerPath: is required.

So why is this required for Java 21 and yet I have not had to include #JavaCompilerPath: 19, C:\Java19\jdk-19.0.2\bin\javac.exe when using Java 19, but just point to the appropriate javac.exe? Perhaps the Java 19 package provided by @Erel contains something which downloading the "three pieces" from elsewhere doesn't.

Again thanks for the assistance - I just love the support users provide via this Forum, but unfortunately moving from from Java 19 to Java 21 still doesn't fix my random video errors using MediaView under Win11.