title: Java 8 - How to reduce the size (lines) of this map operation?
body: <p>I need to get value map for a key, if its not there create new map and insert the key/value. How can i  reduce the number of lines of this operation using java 8 ?</p>
  <pre><code>Map&lt;String, Map&lt;String, String&gt; map = new HashMap();
  Map&lt;String, String&gt; valueMap = map.get(key_1);
  if(valueMap == null) {
      valueMap = new HashMap();
  } 
  valueMap.put(key_2, value);
  map.put(key_1, valueMap);
  </code></pre>