code: private void onNavDrawerItemClicked(final int itemId) {
          if (itemId == mSelectedItem) {
              mDrawerLayout.closeDrawer(GravityCompat.START);
              return;
          }
  
          if (isSpecialItem(itemId)) {
              goToNavDrawerItem(itemId);
          } else {
              // launch the target Activity after a short delay, to allow the close animation to play
              mHandler.postDelayed(new Runnable() {
                  @Override
                  public void run() {
                      goToNavDrawerItem(itemId);
                  }
              }, mConfig.getLaunchDelay());
  
              // change the active item on the list so the user can see the item changed
              setSelectedNavDrawerItem(itemId);
  
              // fade out the main content
  //            if (mMainContent != null && mConfig.getFadeOutDuration() != -1) {
  //                mMainContent.animate().alpha(0).setDuration(mConfig.getFadeOutDuration());
  //            }
          }
  
          mDrawerLayout.closeDrawer(GravityCompat.START);
      }
docs: Call when a nav drawer item is clicked
  
  @param itemId        the id of the item clicked