title: Android Why does my app Force to close?
body: <p>I admit, I'm new at this whole Android stuff. I am trying to make an app but randomly I get Force close errors and I really don't know why. My application has many activities, none of them finish() when I start a new one. I get data from the web (via web services and direct image downloading) and I use AsyncTask a lot. Most of the time it crashes on the asynctask. Here is a sample on how I do things:</p>
  
  <pre><code>private BackTask backTask;
  Activity ctx = this;
  
      public void onCreate(Bundle savedInstanceState) {
              super.onCreate(savedInstanceState);
              setContentView(R.layout.trackslist);
  
          backTask = new BackTask();
              backTask.execute();
      }
  
      protected class BackTask extends AsyncTask&lt;Context, String, myObject&gt;
          {
              @Override
              protected myObject doInBackground(Context... params) 
              {
                   try{
                          if (hasInternet(ctx)==true)
                          {
                              //access the web SERVICE here
                          //initialize myObject WITH result FROM the web
                           return myObject
                         }
                         else
                         {
                              return null
                         }
  
                    }catch(Exception ex){
                         return null;
                  }
              }
  
              @Override
              protected void onPreExecute()
              {
                      super.onPreExecute();
              }
  
              @Override
              protected void onProgressUpdate(String... values) 
              {
                      super.onProgressUpdate(values);
              }
  
              @Override
              protected void onCancelled()
              {
                      super.onCancelled();
              }
  
              @Override
              protected void onPostExecute( myObject result ) 
              {
                      super.onPostExecute(result);
                      if (result==null || result.isEmpty())
                      {
                             //no valid result, show a message
                      }
                      else
                      {
                          //result valid do something with it
                      }
              }
          }
  
       @Override
          public void onPause()
          {
              if (backTask!=null &amp;&amp; ! backTask.isCancelled())
              {
                  backTask.cancel(true);
              }
              super.onPause();
          }
  
      public void btnStartOnClick(View target) {
            Intent intent = new Intent(this, MyNewActivity.class); 
        startActivity(intent);
   }
  </code></pre>
  
  <p>When the activity gets onPause() the task is being canceled. I am not sure what happens during the try/catch if a error appears, from what I've did, it should return null, but I think here I miss something. As I said before, randomly I get a force close even if I am on another Activity. This is really frustrating as I can't offer a app that has this behavior. So, what am I doing wrong ? </p>