Wanted: Help with using JNI/JNA for Native Win32/x86-64.

[Siegfried Heintze]

I'm trying to use https://github.com/jeffheaton/jna-example and https://www.heatonresearch.com/2018/10/02/jna-quickstart.html as a guide and the sample works.

I've tried adding this program generated ChatGPT and I'm getting a stack trace

import com.sun.jna.Native;
import com.sun.jna.platform.win32.Kernel32;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinNT;
import org.jeffheaton.jnaexample.JNAExample;

public class BuildIsComplete {

    public static void main(String[] args) {
        String eventName = args.length > 0 ? args[0] : "BuildInProgressEvent";
        buildIsComplete(eventName);
        System.out.println("Event is set!");
    }
    public static void buildIsComplete(String eventName) {
        Kernel32 kernel32 = Native.loadLibrary("kernel32", Kernel32.class);
        User32 user32 = Native.loadLibrary("user32", User32.class);

        // Constants from the Win32 API
        int EVENT_MODIFY_STATE = 0x2;

        // Open the event object
        WinNT.HANDLE eventHandle = kernel32.OpenEvent(EVENT_MODIFY_STATE, false, eventName);
        if (eventHandle == null) {
            throw new RuntimeException("Failed to open event: " + kernel32.GetLastError());
        }

        try {
            // Set the event
            boolean result = kernel32.SetEvent(eventHandle);
            if (!result) {
                throw new RuntimeException("Failed to set event: " + kernel32.GetLastError());
            }

        } finally {
            // Close the event handle
            kernel32.CloseHandle(eventHandle);
        }
    }
}

I'm getting this error in IntelligJIdea when using Jeff Heaton's pom.xml file.

Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'OpenEvent': The specified procedure could not be found.

	at com.sun.jna.Function.<init>(Function.java:252)
	at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:604)
	at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:580)
	at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:566)
	at com.sun.jna.Library$Handler.invoke(Library.java:243)
	at jdk.proxy1/jdk.proxy1.$Proxy0.OpenEvent(Unknown Source)
	at BuildIsComplete.buildIsComplete(BuildIsComplete.java:23)
	at BuildIsComplete.main(BuildIsComplete.java:11)

Process finished with exit code 1

I think I need to enhance that pom.xml somehow.

Thanks

Siegfried

[Rob Spoor]

I don't think the issue lies in your dependencies. If it were you'd get compiler errors. I think it's more with how you load the libraries.

All examples I've seen use Kernel32.INSTANCE and User32.INSTANCE. These call Native.load instead of Native.loadLibrary (see Kernel32 and User32). The latter is now deprecated. The calls to load also use some default options.

[Siegfried Heintze]

Rob Spoor wrote:I don't think the issue lies in your dependencies. If it were you'd get compiler errors. I think it's more with how you load the libraries.

All examples I've seen use Kernel32.INSTANCE and User32.INSTANCE. These call Native.load instead of Native.loadLibrary (see Kernel32 and User32). The latter is now deprecated. The calls to load also use some default options.

Shame on me! I should have studied Jeff Heatton's working code more closely and trusted ChatGPT less.

My apologies for being sloppy.

Whoa! This is kinda tedious writing the signature for each function you want to call be fore you call it. Surely, someone else has already done this for Kernel32?  Anyone know of where I might find this?

[Rob Spoor]

Unless I'm misreading what you're asking for, the Kernel32 interface I linked to has a lot of methods already. If you miss any, you can always extend the interface, like I've done here: https://github.com/robtimus/windows-registry/blob/master/src/main/java/com/github/robtimus/os/windows/registry/Advapi32Extended.java.