Where to Start Async Task - Android

Question

I'm still learning Java/Android development and I need some guidance to implement an Async task. I'm mostly unsure of where to start it in my program. I have outlined some code below, could someone show me where and how to implement the task? My app sends GPS coordinates to a database every second and I need a separate task so I don't bog down the main thread and risk an ARN error. Here is my code:

This first block is from my main activity. When the button is pressed, a three second countdown is initiated, and when it finishes (onFinish) the user data is sent to one database (SendUserActivity.sendId..., this is actually a class, not an activity, just poorly named) and the app then begins to track the user and send the coordinates to a different database every second (location.startLocation...) (two databases to avoid repeating all of the user's data).

MainActivity.java:

public void onFinish() {
   button.setText("SENT");  
   SendUserActivity.sendId(usr_id1, first, last);                   
   location.startLocation(getBaseContext(), usr_id1);

This is the second block of code from the LocationActivity class (also a class and not an activity, poor naming again). It requests a location update every second and then posts it to a PHP script that inserts it in a MySQL database.

public class LocationActivity {

    private LocationManager locManager;
    private LocationListener locListener;

    public void startLocation(Context context, String usr_id2)
    {   
        final String usr = usr_id2;

    //get a reference to the LocationManager
    locManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);


    //checked to receive updates from the position
    locListener = new LocationListener() {
        public void onLocationChanged(Location location) {
            send(location, usr);
        }
        public void onProviderDisabled(String provider){
            //labelState.setText("Provider OFF");
        }
        public void onProviderEnabled(String provider){
            //labelState.setText("Provider ON ");
        }
        public void onStatusChanged(String provider, int status, Bundle extras){
            //Log.i("", "Provider Status: " + status);
            }
        };
        locManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 0, locListener);
    }

    public void send(Location loc, String usr_id2) {

         Log.i("", String.valueOf(loc.getLatitude() + " - " + String.valueOf(loc.getLongitude())));

         String lat = String.valueOf(loc.getLatitude()); 
         String lon = String.valueOf(loc.getLongitude());

        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://example.com/test/example.php");

         try {
           List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
           nameValuePairs.add(new BasicNameValuePair("lat", lat)); 
           nameValuePairs.add(new BasicNameValuePair("lon", lon));
           nameValuePairs.add(new BasicNameValuePair("id", usr_id2));
           httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
           httpclient.execute(httppost);
         } 
         catch (ClientProtocolException e) {
             // TODO Auto-generated catch block
         } 
         catch (IOException e) {
             // TODO Auto-generated catch block
         }
    }
}

To reiterate my question, how would I implement an async task to send the GPS information to the database? I have read about IntentServices, but some have suggested that I use an async task. Either way, let me know where and how to implement one of these; I'd really appreciate it. Thanks!

basically everything that need to wait for external system, outside the phone need to be in Async. For your case is the send() need to be in async. — Rudy, Mar 01 '12 at 10:41

score 3 · Accepted Answer · edited May 23 '17 at 12:05

3

In this case basically you wrap your send method into the doInBackground() method of asynctask and a result in the onPostExecute(...) will be set into a DB. Make AsyncTask an inner class if you like. There're plenty of examples of how to make an AsyncTask. Here for example just a question

Using AsyncTask with database and

Android AsyncTask and SQLite DB instance.

This site has very good tutorials http://www.vogella.de/articles/AndroidPerformance/article.html

and ofcourse of Mark Murphy's (CommonsWare) https://github.com/commonsguy/cw-lunchlist/blob/master/15-Internet/LunchList/src/apt/tutorial/FeedActivity.java

Cheers

edited May 23 '17 at 12:05

Community

1
1

answered Mar 01 '12 at 10:31

Sergey Benner

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Shouldn't I have an entire task for the `LocationActivity` class? – mkyong Mar 01 '12 at 10:50
not really but still possible check here http://about-android.blogspot.com/2010/04/find-current-location-in-android-gps.html ... and here http://stackoverflow.com/questions/8253887/how-to-excute-asynctask-inside-onlocationchanged-method-in-android and check this one --- I guess its your perfect case ://stackoverflow.com/questions/7617957/should-i-create-service-for-gps-tracking-app – Sergey Benner Mar 01 '12 at 10:54
Also, since the send method is called every second, will this create a new task each time? – mkyong Mar 01 '12 at 10:56
The new task is created when you need it at any place read here http://stackoverflow.com/questions/6373826/execute-asynctask-several-times and more to that http://stackoverflow.com/questions/2711183/asynctask-threading-rule-can-it-really-only-be-used-once. You just call its execute(....) method with parameters at this point.You shouldn't care about its threads either. Read this post http://stackoverflow.com/questions/3077461/asynctask-threads-never-die-android – Sergey Benner Mar 01 '12 at 11:12

Adam · Answer 2 · 2012-03-01T10:43:09.490

I think that a "GPS collector" is more suited to a Service.

Your service could look like:

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Binder;
import android.os.Bundle;
import android.os.IBinder;

public class GPSCollectService extends Service implements LocationListener{
private LocationManager mLocationManager;

public class GPSBinder extends Binder {
    GPSCollectService getService() {
        return GPSCollectService.this;
    }
}

@Override
public IBinder onBind(Intent intent) {
    return mBinder;
}

private final IBinder mBinder = new GPSBinder();

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    return START_STICKY;
}

@Override
public void onCreate() {
    startservice();
}

@Override
public void onDestroy(){
    mLocationManager.removeUpdates(this);
    mLocationManager = null;
}

private void startservice() {
    mLocationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
    mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 0, this);   
}

public void onLocationChanged(Location arg0) {
    if (arg0 != null){
        //Your database storing code here
        }
    }

public void onProviderDisabled(String arg0) {}
public void onProviderEnabled(String arg0) {}
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {}
}

and in your main activity:

private Intent msvcGPSCollect = null;

@Override
public void onDestroy(){
    finishServices();

    super.onDestroy();
}

private void startBackgroundServices(){
    msvcGPSCollect = new Intent(this, GPSCollectService.class);
    startService(msvcGPSCollect);
}

private void finishServices(){
    if (msvcGPSCollect != null)
        stopService(msvcGPSCollect);
}

EDIT: I've not actually answered your question!

Where I've put:

\\ Your database storing code here

you'll need to call your own Async Task.

Example of an async task call:

PushGPSAsync myAsyncTask = new PushGPSAsync();
myAsyncTask.execute();

Example of an async task:

public class PushGPSAsync extends AsyncTask<Void, Void, Boolean>{
    @Override
    protected Boolean doInBackground(Void... params){
        pushGPS();
        return null;
    }

    @Override
    public void onPostExecute(Boolean result){
        //Call a post execute function here
    }
}

private boolean pushGPS(Void... params){
    //store the GPS
}

Where to Start Async Task - Android

2 Answers2