title: Recycler view adapter not reflecting changes
body: <p>So I have a recycler view adapter set up in my MainActivity. That adapter is hooked up to an arraylist of a custom object I made called group.</p>
  
  <pre><code>public static RecyclerView.Adapter groupsListAdapter;
  public ArrayList&lt;Group&gt; myGroups;
  </code></pre>
  
  <p>//inside onCreate of Main Activity</p>
  
  <pre><code>groupsListAdapter = new MyAdapter(myGroups);
  </code></pre>
  
  <p>In a different Activity, I am updating the contents of this arraylist, first by passing it through the intent. </p>
  
  <pre><code>Intent groupCreationIntent = new Intent(MainActivity.this, NewGroupActivity.class);
          groupCreationIntent.putExtra("groupsList",myGroups);
          startActivity(groupCreationIntent);
  </code></pre>
  
  <p>And then updating it in the other activity.</p>
  
  <pre><code>private ArrayList&lt;Group&gt; groups;
  </code></pre>
  
  <p>//in oncreate method of other activity</p>
  
  <pre><code>groups = (ArrayList&lt;Group&gt;) getIntent().getSerializableExtra("groupsList");
  </code></pre>
  
  <p>When going back to the previous activity (the second activity is used for entering some information and syncing it with my database) I run this code.</p>
  
  <pre><code>groups.add(myGroup);
  MainActivity.groupsListAdapter.notifyDataSetChanged();
  finish();
  </code></pre>
  
  <p>The problem is that the list adapter is not reflecting the changes, nothing is appearing in my list once i return to the main activity. What am I doing wrong?</p>