title: Refresh activity on back button
body: <p>I have an activity A which has a feed kind of interface. There is a text on each of these feed items which indicate the number of comments on that item. Now if on that item, I click comment and go to new activity B, add comment through activity B and press back to go back to activity A. When I add the comment, the info is reflected in the backend. But the problem is, when I press back, the saved instance of activity A shows in which the number of comments is not updated because there is no call to backend from activity A.</p>
  
  <p>What is the standard way of doing something like this? How should I refresh the previous screen in activity stack on pressing back on some activity?</p>
  
  <p>Here are some relevant code snippets:</p>
  
  <pre><code>Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
          setSupportActionBar(toolbar);
          getSupportActionBar().setDisplayHomeAsUpEnabled(true);
          getSupportActionBar().setHomeAsUpIndicator(R.drawable.gallery_page_button_back);
  
  
  @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          // Handle action bar item clicks here. The action bar will
          // automatically handle clicks on the Home/Up button, so long
          // as you specify a parent activity in AndroidManifest.xml.
          int id = item.getItemId();
  
          if(id == android.R.id.home) {
              this.finish();
              return true;
          }
  
          //noinspection SimplifiableIfStatement
          if (id == R.id.action_settings) {
              return true;
          }
  
          return super.onOptionsItemSelected(item);
      }
  </code></pre>