title: I got stuck on the onBackPressed() in AsyncTask
body: <p>I am start working on the Asynctask Demo. What I want is , "When I press the back button in the android device I want to stop the task which is running in the app  "</p>
  
  <p>I set up this thing on the onBackPressed() method but after this in the Logcat  Task doesn't stop .</p>
  
  <p>Where am I make  the mistake , help me out of this ?</p>
  
  <pre><code>public class Activity1 extends Activity {
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      new CountDownTask().execute();
  }
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      getMenuInflater().inflate(R.menu.activity_main, menu);
      return true;
  }
  @Override
  public void onBackPressed() {
      super.onBackPressed();
      new CountDownTask().cancel(true);
  }
  
  private class CountDownTask extends AsyncTask&lt;Void, Integer, Void&gt;{
      @Override
      protected void onPreExecute() {
          TextView tvCounter = (TextView) findViewById(R.id.tv_counter);
          tvCounter.setText("START");
      }
  
      @Override
      protected Void doInBackground(Void... params) {
          for(int i=15;i&gt;=0;i--){
              try {
                  Thread.sleep(1000);
                  publishProgress(i);
                  Log.e("Aka", String.valueOf(i));
                  if(isCancelled()){
                      break;
                  }
              } catch (InterruptedException e) {
              }
          }
          return null;
      }
  
      @Override
      protected void onProgressUpdate(Integer... values) {
          TextView tvCounter = (TextView) findViewById(R.id.tv_counter);
  
          tvCounter.setText( Integer.toString(values[0].intValue()));         
      }
  
      @Override
      protected void onPostExecute(Void result) {
          TextView tvCounter = (TextView) findViewById(R.id.tv_counter);
          tvCounter.setText("DONE");          
      }       
  }
  </code></pre>
  
  <p>}</p>