Creating HelloWord Java plugin

Unity Engine
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1

Hi.
Can someone guide me to a tutorial covering creating simplest Java plugin? I can do for example:

jo = new AndroidJavaObject("java.lang.String", "some_string");

But when I am trying to access custom class from my own .jar the application is crashing - I must be doing something wrong when it comes to creating .jar archive. I am using Eclipse currently.

2

That class is for intersession communication on the mobile Android platform. You can’t use a standalone application on a computer to communicate with a Java program using that method.

3

Hi.
I am not trying to run it as standalone or in the editor - I am publishing for Android and pushing it to a device. As I mentioned - using build-in Java classes is working for me, but I have problems when I want to reference some classes from my custom .jar.

4

OK, I’m in exactly the same situation now. Did you ever resolve this?

I’ve created my jar file, imported it in, but my Unity code can’t find the Java class.

I’m wondering:

Does the name of the package and class matter? These functions are not extending unity player activity in any way, they’re standalone functions.

Do you have to sign the Jar a specific way in order for it to work? In fact Eclipse is not asking me to sign- the Jar files appear without me needing to sign anything.

5

Likewise, having the same issue. Just to narrow it down, I’ve tried using the example Java Android plugin from the Unity site. It works when I use the provided .jar, but crashes if I compile my own .jar from the same source code and try to use that.

I have a feeling there must be some particular way you have to build/sign the .jar, but there doesn’t seem to be any info about that. And the forums have been dead silent on the matter.

6

When I tried to build my own plugin this link helped me.

VERY Important : you need to sign your plugin with JDK 1.6 (1.7 doesn’t work at all for me at least).

But I recommand you tu use Eclipse with the ADT plugin for building your own .JAR (just include the unity libraries in Eclipse located at <PATH_INSTALL_UNITY>\Editor\Data\PlaybackEngines\androidplayer\bin\classes.jar)

7

Thanks! That had the step I was missing - sign your plugin using Java 1.6