title: Change the alpha of recyclerview item with beacon detection
body: <p>In a <code>Fragment</code> I have a list of items construct with <code>RecyclerView</code> (adapter and viewholder).
  Each item of the list is linked with a estimote beacon.
  So i want to highlight the item view (setAlpha or add a imageView) when the beacon is detected.</p>
  
  <p>The beacon detection is in the fragment file : </p>
  
  <pre><code>beaconManager.setRangingListener(new BeaconManager.RangingListener() {
              @Override
              public void onBeaconsDiscovered(Region region, List&lt;Beacon&gt; list) {
                  if (!list.isEmpty()) {
                      Beacon nearestBeacon = list.get(0);   
                      replaceIconBeaconCard(nearestBeacon);                     
                      Log.d("Airport", "Nearest places: " + nearestBeacon);
                  }
              }
          });
  </code></pre>
  
  <p>Actually, I display a beacon icon on the item view. But the purpose is to highlight the detected item and put a alpha on the others items.</p>
  
  <pre><code>private void replaceIconBeaconCard(Beacon beacon){
          for(SItem item: items) {
              if (!item.getMajor().equals("")) {
                  int i = item.getId().intValue();
                  SCard card = listCards.get(i-1);
                  if (Integer.parseInt(item.getMajor()) == beacon.getMajor()) {
                      rv.getLayoutManager().scrollToPosition(i);                    
                      int resID = getResources().getIdentifier("beacon_ice", "drawable", getActivity().getPackageName());
                      card.setField_1(resID);
                  } else {
                      card.setField_1(Color.TRANSPARENT);
                  }
              }
          }
          mAdapter.notifyDataSetChanged();
      }
  </code></pre>
  
  <p>I don't know how I can access to item layout and change the alpha.</p>