Use a .jar java library API in C#?

Question

I'm an entry level programmer so please be descriptive in your responses.

I am trying to use a Java API given as a .jar file in my C# .net application. I don't know much Java, but this .jar file says "no main-class manifest attribute" when I try to run it so this means its a library? This Java API also comes with a .java file which shows how to use the library but I cannot see the code inside the .jar.

I found this question on this site, and one of the answers reads, "In simple way you can pack your java classes to jar file then In C# use Process class for execute and map IO stream." I am semi-familiar with the Process class in C# but I don't understand how I could use it to use a Java library in my C# .net project.

Is this possible? or was that answer incorrect?

If so, could you explain how I can use the .jar library in my C# app.

Whit Waldo · Accepted Answer · 2017-02-05 21:26:58Z

77

You can do it using IVKM.Net. IVKM.NET includes an application called ikvmc. Here’s the documentation for this tool:

http://www.ikvm.net/userguide/ikvmc.html

To use it compile your java code into a Jar.

Then run the ikvmc program:

ikvmc myCode.jar

If your jar contains a main() function, it will be converted into an exe that can be run on the CLR. Otherwise it will be converted into dll’s. To use the dll’s in your project just add them as references in Visual Studio and the same API that was available to you in Java will be accessible in your .Net application.

You can also include the IKVM.GNU.Classpath.dll dll from ikvmc and use the standard java class libraries in your application.

edited Feb 5, 2017 at 21:26

Whit Waldo

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answered Feb 4, 2009 at 16:58

Stephen Curial

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6 Comments

timmyg Over a year ago

thanks I will give it a try. once i have the .dll and I import it into my project should I call the library's function using Pinvoke?

Stephen Curial Over a year ago

You don't need to use pinvoke. You should be able to simply call the api just like you would as if it was orig written in C#.

LDomagala Over a year ago

you should change "run on the CIL" into "run on the CLR"

Cragly Over a year ago

Good stuff, just used it in my .net app and worked like a charm. Thanks

Joel B Over a year ago

I'm pretty sure you just made me an office hero.

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Rad · Accepted Answer · 2009-02-04 17:04:30Z

7

Have a look at IKVM ... it has tools to give you some level of interop. When you say Java API I assume you want to call some functionality from the jar rather than just execute it

answered Feb 4, 2009 at 17:04

Rad

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1 Comment

timmyg Over a year ago

Correct, the .jar doesn't execute, it reports an error message that reads, "Failed to load Main-Class manifest attribute from ...". Once I have the .jar converted to .dll I'm going to attempt to use it the same as the java coded example using the .jar.

Maciej Pulikowski · Accepted Answer · 2020-01-01 14:23:05Z

2

You could use IKVM.NET - http://www.ikvm.net/userguide/ikvmc.html

On the official website in download - you can get ikvmbin-7.2.4630.5 (Works up to Java 7)

However, on the owner's blog, you can download a newer version. http://weblog.ikvm.net/default.aspx - You can get ikvmbin-8.1.5717.0 (Works up to Java 8)

To create dll/exe use:

ikvmc hello.jar
On the other hand, if you can edit .jar lib (you created it) you could use http://jni4net.com/ project.

answered Jan 1, 2020 at 14:23

Maciej Pulikowski

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