Java plugin on Unity3D cant start new thread

Question

I have a java plugin that i use on simple java apps that i develop. This plugin starts a new thread that also uses networking.

The class that executes is implementing Runnable and start the thread this way:

AsyncTask.execute(this);

This works fine with java apps and run without any problem, but, when i try to run this plugin with Unity3D, it throws an error and wont run my plugin

the code executed in Unity3D:

var token="AbCd123456789";
var jo = new AndroidJavaObject("com.edealya.lib.AppayableUnityAdapter");
jo.Call("runApplayble",token);

the runAppayable method is:

public void runAppayable(String token){
DeviceIdentifier edDevice = new DeviceIdentifier(
                                this.getApplicationContext(),token);
edDevice.update();

}

and edDevice.update(); is the method that starts the new thread.

I/Unity   (27624): Exception: java.lang.RuntimeException: Can't create handler inside     thread that has not called Looper.prepare()
I/Unity   (27624):   at UnityEngine.AndroidJNISafe.CheckException () [0x00000] in   <filename unknown>:0 
I/Unity   (27624):   at UnityEngine.AndroidJNISafe.NewObject (IntPtr clazz, IntPtr methodID, UnityEngine.jvalue[] args) [0x00000] in <filename unknown>:0 
I/Unity   (27624):   at UnityEngine.AndroidJavaObject._AndroidJavaObject (System.String className, System.Object[] args) [0x00000] in <filename unknown>:0 
I/Unity   (27624):   at UnityEngine.AndroidJavaObject..ctor (System.String className, System.Object[] args) [0x00000] in <filename unknown>:0 
I/Unity   (27624):   at ReflectionFx.startAppayable () [0x00006] in /Users/Shared/Unity/4-0_AngryBots/Assets/Scripts/Fx/ReflectionFx.cs:30 
I/Unity   (27624):   at ReflectionFx.Start () [0x00000] in /Users/Shared/Unity/4-0_AngryBots/Assets/Scripts/Fx/ReflectionFx.cs:38 

how can i solve this?

Answer 1

AsyncTask must be started on UiThread or thread that have Looper, try to start it with

myActivity.runOnUiThread(new Runnable(){AsyncTask.execute(this);})

or call Looper.prepare() on thread You are before starting it

Answer 2

Just by reading the stacktrace it looks to me like the Unity layer is catching runtime exceptions and dumping out something different.

I've seen a similar looking stacktrace with NullPointerException: instead of the stack trace that traces back to the place in my code where the problem is, I see this Unity JNI stacktrace.

Can anyone explain why that is and how to get Unity to dump out the proper stacktrace?