title: How best to use ordered Map in Java 8
body: <p>What would be the best declaration for the variable below in Java 8?</p>
  <p><em>In Dart:</em></p>
  <pre><code>const Map&lt;Integer,Map&lt;String, String&gt;&gt; data = {
  1: {'name': 'John', 'age' : '20'},
  2: {'name': 'Mary', 'age' : '30'}
  }
  </code></pre>