将Doubles的ArrayList传递给另一个类

Question

I was looking for some help I've spent the last few days trying to pass an ArrayList of Doubles into another class from an AsyncTask with no success and I am now thinking I should pass the array back to the mainActivity and then run it to the ProxAlert class from there. Is this the way to do it or am I over complicating it? Thanks for your help.

try{
        ArrayList<LatLonPair> nPosition = new ArrayList<LatLonPair>();
        JSONArray jArray = new JSONArray(result);


        System.out.println("Length"+ jArray.length());
        Log.d("DB","Length"+jArray.length());

        for(int i=0; i<jArray.length(); i++){

                JSONObject json_data = null;

                json_data = jArray.getJSONObject(i);
                int eventID = i +1;
                String title = json_data.getString("Title");
                double latitude = json_data.getDouble("Lat"); 
                double longitude = json_data.getDouble("Lon"); 

                LatLonPair p = new LatLonPair(latitude , longitude);
                nPosition.add(p);


                //System.out.println(eventID+"&"+latitude+"&"+longitude);
                System.out.println("this" + p.printPoints());                        
        }    

    }       
    catch(JSONException e){
            Log.e("log_tag", "Error parsing data "+e.toString());
            Log.e("log_tag","Failed data as:\n"+result);                
    }    

        return nPosition;           
}

@Override
protected void onPostExecute(ArrayList<LatLonPair> result) {
    new ProxAlert().registerIntents(result);
    super.onPostExecute(result);
    //Intent i = new Intent();
    //i.putParcelableArrayListExtra("nPositon",(ArrayList<LatLonPair>) result);

    //startARActivity();
}

I went to transfer it to the main thread but I would have to make it Parcelable and I'm just unsure as the most direct approach. Sorry the error that I get is

09-18 12:27:16.605: E/AndroidRuntime(20122): java.lang.IllegalStateException: System      services not available to Activities before onCreate()
 09-18 12:27:16.605: E/AndroidRuntime(20122):   at android.app.Activity.getSystemService(Activity.java:3562)
 09-18 12:27:16.605: E/AndroidRuntime(20122):   at com.example.test.ProxAlert.setProximityAlert(ProxAlert.java:51)
09-18 12:27:16.605: E/AndroidRuntime(20122):    at com.example.test.ProxAlert.registerIntents(ProxAlert.java:37)
09-18 12:27:16.605: E/AndroidRuntime(20122):    at com.example.test.retrieveDB.onPostExecute(retrieveDB.java:116)
09-18 12:27:16.605: E/AndroidRuntime(20122):    at com.example.test.retrieveDB.onPostExecute(retrieveDB.java:1)
09-18 12:27:16.605: E/AndroidRuntime(20122):    at android.os.AsyncTask.finish(AsyncTask.java:417)
09-18 12:27:16.605: E/AndroidRuntime(20122):    at android.os.AsyncTask.access$300(AsyncTask.java:127)
09-18 12:27:16.605: E/AndroidRuntime(20122):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)

Its instantiating before the onCreate(), thats why i was thinking it might be best to passed the array back to the main activity and then to the proxAlert.class

Answer 1

The exception you get is the result of trying to get system services in the ProxAlert activity before the activity's onCreate() was called. Your AsyncTask doesn't respect the activity life cycle. You cannot instantiate an activity with new .

If you want to use other activites, then you must use Intents in the way it is described in this post: Pass ArrayList<Double> from one activity to another activity on android