title: RxJava and Observable on retrofit API call
body: <p>I am new to RxJava and want to understand the Observable. So, I am making one API call using retrofit and I am observing changes on the result so my questions are:</p>
  
  <ol>
  <li>Does it make a continues API call to fetch the latest result from the server? </li>
  <li>If yes then how frequently it is calling?</li>
  <li>Is it call once then what's the use to observe the data?</li>
  <li>Is it call once then we should use RxJava just to save a couple of lines in our code? We can simply use live data in this case.</li>
  <li>Does it call once per lifecycle of the activity i.e(if activity gets killed and open again then it will fetch the new result?) </li>
  </ol>
  
  <p>Here is a code snippet:</p>
  
  <pre><code>// fetching list of recipes
   mRecipeListViewModel.getRecipes().observe(this, new Observer&lt;List&lt;Recipe&gt;&gt;() {
              @Override
              public void onChanged(@Nullable List&lt;Recipe&gt; recipes) {
                  // showing list of recipes
              }
          });
  </code></pre>