Unity3d Android plugin static AsyncTask issue

Question

I'm developing an application for android on Unity3d engine. This application must connect to my server on PC via network sockets. I found some Unity3d plugin examples for Android. Based on them I've written some code on c# for Unity3d and on Java for Android. I found out that network operations must not run in UI-thread in Android application. So I have to use AsynTask for network requests. Also I've tried to call non-static methods from c# script but they don't return any data. Only static calls return data from java application. So my AsyncTask class is static. But when I call static function with AsyncTask job to get data through network my application is crashed. I receive errors. Could you help me to fix my problems? I see two ways to fix this problem: 1) Change my c# code for Unity3d to get data through Non-Static method calls. Change all methods to Non-Static in Java code. 2) Change my Java code to work with static methods and static AsyncTask.

My c# script AndroidClientPlugin.cs:

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;

public class AndroidClientPlugin : MonoBehaviour {
    private float TEST;

    private AndroidJavaClass cls_UnityPlayer;
    private AndroidJavaObject obj_Activity;
    private AndroidJavaClass cls_CompassActivity;
    // Use this for initialization
    void Start () {

        AndroidJNI.AttachCurrentThread();
        cls_UnityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
        obj_Activity = cls_UnityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
        cls_CompassActivity = new AndroidJavaClass("com.lab.Android.AndroidClientPlugin");

        cls_CompassActivity.SetStatic<String>("ServerAddressValue", "192.168.1.5");
        cls_CompassActivity.SetStatic<String>("ServerPortValue", "8881");

    }
    void OnGUI() {
        GUI.Label(new Rect(Screen.width / 2 -200, Screen.height / 2, 400,100), "x = " + TEST.ToString());
    }
    void Update()
    {
        if(cls_CompassActivity.CallStatic<bool>("GetData"))
        {
            TEST = cls_CompassActivity.CallStatic<float>("getPosX");
        }
    }
}

My Java script AndroidClientPlugin.java:

package com.lab.Android;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import com.unity3d.player.UnityPlayer;
import com.unity3d.player.UnityPlayerActivity;

import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Looper;
import android.os.StrictMode;
import android.util.Log;
import android.content.Context;
import android.content.Intent;
import android.app.Activity;

public class AndroidClientPlugin  extends UnityPlayerActivity {

    //Server address parameters
    public  static String ServerAddressValue;
    public  static String ServerPortValue;
    //Tracker parameters
    public  static String vServerName;
    public  static String vSensorNumber;

    private  static SensorData vTaskResult;

    public static cTask BackgroundTask;

    @Override
    protected void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        //set thread strict mode off
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);

        vTaskResult = new SensorData(); 
        ServerAddressValue = "192.168.1.5";
        ServerPortValue = "8881";
        vServerName = "Tracker0";
        vSensorNumber = "0";       
        BackgroundTask = new cTask();        
    }

    @Override
    protected void onResume()
    {
        super.onResume();
    }

    @Override
    protected void onStop()
    {
        super.onStop();
    }

    public static boolean GetData()
    {    
        cTaskResult taskResult = new cTaskResult();
        taskResult = BackgroundTask.DoAsyncTask(ServerAddressValue, ServerPortValue, vServerName, vSensorNumber);
        vTaskResult = taskResult.ResultData;
        return taskResult.DataIsReady;
    }


    public static class cTaskResult
    {
        public boolean DataIsReady;
        public SensorData ResultData;
        public cTaskResult()
        {
            DataIsReady = false;
            ResultData = new SensorData();  
        }   
    }

    public static class cTask
    {       
        public cTask()
        {               
        }
        public cTaskResult DoAsyncTask(String serverAddress, String serverPort, String trackerName, String trackerSensorNumber)
        {
            cTaskResult Result = new cTaskResult();     
            GetDataTask Task;
            Task = new GetDataTask();       
            Task.execute(serverAddress, serverPort, trackerName, trackerSensorNumber, Result);          
            try {
                Result = Task.get(1, TimeUnit.SECONDS);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (ExecutionException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (TimeoutException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return Result;          
        }

        public static class GetDataTask extends AsyncTask<Object, Void, cTaskResult> 
        {
            @Override
            protected void onPreExecute() {
              super.onPreExecute();
            }

            @Override
            protected cTaskResult doInBackground(Object... params) {
                cTaskResult TMPData = new cTaskResult();
                //doing network requests
                //TMPData.DataIsReady = NetClient.getInstance().GetData((String)params[0], (String)params[1], (String)params[2],  Integer.valueOf((String)params[3]), TMPData.ResultData);
                //TMPData is a result of network operations
                TMPData.DataIsReady = true;
                TMPData.ResultData = new SensorData();

                return TMPData;
            }

            @Override
            protected void onPostExecute(cTaskResult result) {
              super.onPostExecute(result);
            }
          }
    }

    public static float getPosX()
    {
        return vTaskResult.posX;
    }   
}

Debug messages:

    09-11 12:56:05.514: E/CMarlinMediator(137): Error : MarlinMediator Failed to get TrustedTime
09-11 12:56:05.594: E/CMarlinMediator(137): Error : MarlinMediator Failed to get TrustedTime
09-11 12:56:12.184: E/Adreno200-EGL(7590): <qeglDrvAPI_eglGetConfigAttrib:484>: EGL_BAD_ATTRIBUTE
09-11 12:56:12.184: E/Adreno200-EGL(7590): <qeglDrvAPI_eglGetConfigAttrib:484>: EGL_BAD_ATTRIBUTE
09-11 12:56:12.184: E/Adreno200-EGL(7590): <qeglDrvAPI_eglGetConfigAttrib:484>: EGL_BAD_ATTRIBUTE
09-11 12:56:14.304: E/AndroidRuntime(7590): FATAL EXCEPTION: GLThread 741
09-11 12:56:14.304: E/AndroidRuntime(7590): java.lang.ExceptionInInitializerError
09-11 12:56:14.304: E/AndroidRuntime(7590):     at com.lab.Android.AndroidClientPlugin$cTask.DoAsyncTask(AndroidClientPlugin.java:128)
09-11 12:56:14.304: E/AndroidRuntime(7590):     at com.lab.Android.AndroidClientPlugin.GetData(AndroidClientPlugin.java:79)
09-11 12:56:14.304: E/AndroidRuntime(7590):     at com.unity3d.player.UnityPlayer.nativeRender(Native Method)
09-11 12:56:14.304: E/AndroidRuntime(7590):     at com.unity3d.player.UnityPlayer.onDrawFrame(Unknown Source)
09-11 12:56:14.304: E/AndroidRuntime(7590):     at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1462)
09-11 12:56:14.304: E/AndroidRuntime(7590):     at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1216)
09-11 12:56:14.304: E/AndroidRuntime(7590): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
09-11 12:56:14.304: E/AndroidRuntime(7590):     at android.os.Handler.<init>(Handler.java:121)
09-11 12:56:14.304: E/AndroidRuntime(7590):     at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:607)
09-11 12:56:14.304: E/AndroidRuntime(7590):     at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:607)
09-11 12:56:14.304: E/AndroidRuntime(7590):     at android.os.AsyncTask.<clinit>(AsyncTask.java:190)
09-11 12:56:14.304: E/AndroidRuntime(7590):     ... 6 more
09-11 12:56:15.194: E/CMarlinMediator(137): Error : MarlinMediator Failed to get TrustedTime
09-11 12:56:15.234: E/CMarlinMediator(137): Error : MarlinMediator Failed to get TrustedTime

Answer 1

First of all, why you call android code in Update function? Since it will be called every frame.

Maybe you should put some flag that indicates the native-code is being running, and dont called it twice.

And about your problem, as far as I know, AsyncTask creation and task running must be called within the UI-Thread. The problems are:

1. You call static method AndroidClientPlugin.GetData within the Update method in Unity. As far as I know, that is not the same thread with the UI-Thread of android. So you called it within Unity's own thread, and:
2. You create and running the AsyncTask within the Unity3d's thread, so it will be error.

My solution is (you can try it):

public static void GetData()
{    
    //this will be called on UIThread of Android
    com.unity3d.player.UnityPlayer.currentActivity.runOnUiThread(new Runnable(){
        public void run(){
            cTaskResult taskResult = new cTaskResult();
            taskResult = BackgroundTask.DoAsyncTask(ServerAddressValue, ServerPortValue, vServerName, vSensorNumber);
            vTaskResult = taskResult.ResultData;
                com.unity3d.player.UnityPlayer.currentActivity.SendMessage("YourGameObjectName", "YourMethodName", taskResult.DataIsReady);
            //return taskResult.DataIsReady;    
        }
    });

}