title: AsyncTask with Dialog to internet unavailable then end entire app
body: <p>I'm developing an app that makes requests to a web service more often. What I want to do is, when internet is not available or disconnected then instead of proceeding to request; app should show a message indicating unavailability of internet and kill itself. I've this code working fine with me - </p>
  
  <pre><code>public GetXMLFromServer(Context context, GetXMLCallback gc,
            ArrayList&lt;NameValuePair&gt; params, String message) {
      this.context = context;
      this.gc = gc;
      this.postParameters = params;
      progressDialog = new ProgressDialog(this.context);
      this.message = message;
  }
  
  protected void onPreExecute() {
      progressDialog.setTitle("Please Wait");
      progressDialog.setMessage(message);
      progressDialog.show();
  }
  
  @Override
  protected void onPostExecute(String result) {
      progressDialog.dismiss();
      gc.onSuccess(result);   
  }
  
  @Override
  protected String doInBackground(String... params) {
      String response = null;     
      try{
          ConnectivityManager cm = (ConnectivityManager) this.context
                  .getSystemService(Context.CONNECTIVITY_SERVICE);
          NetworkInfo netInfo = cm.getActiveNetworkInfo();
          if (netInfo != null &amp;&amp; netInfo.isConnectedOrConnecting()) {         
          } else if (netInfo == null) {
              AlertDialog alertDialog = new AlertDialog.Builder(this.context).create();
              alertDialog.setTitle("Connection Problem");
              alertDialog.setMessage("You are not connected to Internet");
              alertDialog.setButton("Exit",
                      new DialogInterface.OnClickListener() {
                          public void onClick(DialogInterface dialog, int which) {                                
                              isAvailable=false;
                              return;
                          }
                      });
              alertDialog.show();
          }
  
          /*if(isAvailable==false){
              then finish the calling activity or entire app.
          }*/
      }catch(Exception e){
  
      }
      try {
          response = CustomHttpClient.executeHttpPost(this.urlToFetch,
                  this.postParameters);           
      } catch (Exception e) {
          e.printStackTrace();
      }
      return response;
  }
    }`
  </code></pre>
  
  <p>Now my problem is, I can't figure out how to end entire app or calling activity before  making a request and crashing the app because of there is unavailability of internet. (Commented part of code is where I want to stop app and end it)</p>