Trying Java 19 in Xojo

Let’s try the MBS Xojo Java Plugin for Xojo with Java 19.0.2. We go to the download page and pick the jdk-19_macos-aarch64_bin.dmg file from Oracle’s download page.

We get the installer, run it and after it finishes, Java is installed. Let’s try and open Terminal and run the

java --version

command to see what version we got:

java 19.0.2 2023-01-17 Java™ SE Runtime Environment (build 19.0.2+7-44) Java HotSpot™ 64-Bit Server VM (build 19.0.2+7-44, mixed mode, sharing)

The files are all installed into a folder in your /Library folder, e.g.


so the libjvm.dylib is in that folder and we load it in our project here:


Put this before calling the JavaVMMBS constructor. You still pass version 1.4 there as this is the version of the jni API and this part of Java hasn’t changed or 10 years. The later Java versions changed compiler and added framework classes, but didn’t change the jni interface.

We can query java.version or os.version here:

#If TargetMacOS Then
	// change the path for your installation!
#ElseIf TargetLinux Then
	// change path for your linux PC!

// init Java
Dim options() As String
Dim javaVm As New JavaVMMBS(JavaVMMBS.JNI_VERSION_1_4, options, True)

// Get system class
Dim System As JavaClassMBS = javaVm.FindClass("java/lang/System")

If System <> Nil Then
	// query method
	Dim transfomerGetPropertyId As JavaMethodMBS = System.GetStaticMethod("getProperty", "(Ljava/lang/String;)Ljava/lang/String;")
	If transfomerGetPropertyId <> Nil Then
		// make parameters
		Dim keyString As JavaStringMBS = javaVm.NewStringUTF8("java.version")
		Dim m As New MemoryBlock(8)
		// run it
		Dim r As JavaObjectMBS = System.CallStaticObjectMethod(transfomerGetPropertyId, m)
		If r<>Nil Then
			// show result
			Dim s As JavaStringMBS = JavaStringMBS(r)
			MsgBox s.CopyStringUTF
		End If
	End If
End If

When we run this, it shows the version 19.0.2 here for the java.version property. Please note that we had recently to update the .long() calls to .Int64Value() since Xojo deprecated the old calls. If the library isn’t found and loaded, the application may fail and get killed by macOS for accessing Java.framework, which is the default way to load.

Please note that we have to check the platform used for macOS since running an example compiler for Intel with a Java library built for Apple Silicon. The application may just quit in that case or better repport an error.

We’ll fix the Java.framework thing. Let us know if you have questions. The bug fixes for Java 19 on macOS comes into version 23.2.

1 Like

what file do I need to include for windows version??

your sample only shown Mac and linux.

I think this may be this one:

C:\Program Files\Java\jdk-19\bin\server\jvm.dll

But usually I would expect the plugin finds it via the registry automatically.

thanks… Christian…
I have already tested your sample code with Java 20

20 already?

I just wrote an article about 19, which was current a few days ago…
Anyway, the version usually doesn’t matter for us.

It’s all Java 1.4 from the point of view of the plugin :slight_smile:

Java 19 out a few months ago… Java 20 just out last week.
I notice it is java 1.4 from the plugin view.