title: Android why Fragments should not directly communicate with each other?
body: <p>I have an <code>Activity A</code> hosting two main <code>Fragment F1 and F2</code>. Both <code>F1</code> and <code>F2</code> have nested <code>Fragment</code>, each with its own <code>Listener</code> interface for exchanging data.</p>
  
  <p>From what I understood from the answer to <a href="https://stackoverflow.com/questions/23142956/sending-data-from-nested-fragments-to-parent-fragment">this question</a>, the activity <code>A</code>:</p>
  
  <ul>
  <li><p>needs to know every single interface declared by the fragments hosted by <code>F1</code> and <code>F2</code></p></li>
  <li><p>needs to route the events generated by the fragments in <code>F1</code> and <code>F2</code> to the correct main fragment, <code>F1</code> or <code>F2</code>.</p></li>
  </ul>
  
  <p>If I understood correctly, there is no modularity in this approach: the activity needs to know everything about both the fragments it hosts (<code>F1</code> and <code>F2</code>) and the fragments that are nested in <code>F1</code> and <code>F2</code>. </p>
  
  <p>Am I correct? For sure, I am very confused ...</p>