title: How to retrieve contents from Map<String, Map<String,String>>?
body: <pre><code>Map&lt;String, Map&lt;String,String&gt;&gt; regMap = new HashMap&lt;String, Map&lt;String,String&gt;&gt;();
  </code></pre>
  
  <p>How do I retrieve contents from <code>regMap</code>? Is there any data structure where I can store three related things ?</p>