title: What data structure to use?
body: <p>I need to represent the below data (in Java):</p>
  
  <ul>
  <li>2012 (Year)
  <ul>
  <li>01(Month)
  <ul>
  <li>01 (Day)
  <ul>
  <li>Hello I am a string</li>
  </ul></li>
  <li>02</li>
  <li>...</li>
  </ul></li>
  <li>02</li>
  <li>03</li>
  <li>04 </li>
  <li>…</li>
  </ul></li>
  </ul>
  
  <p>I was thinking of using a TreeMap, but not sure how. Any ideas?</p>