title: Use Streams to return Boolean if all the List values in a Map are empty/not-empty
body: <p>Given a <a href="http://docs.oracle.com/javase/8/docs/api/java/util/Map.html" rel="noreferrer"><code>Map</code></a> mapping a String to a <a href="http://docs.oracle.com/javase/8/docs/api/java/util/List.html" rel="noreferrer"><code>List</code></a>, is there a way to use <a href="http://docs.oracle.com/javase/tutorial/collections/streams/index.html" rel="noreferrer">Java Streams</a> to return a Boolean where TRUE means one or more list had elements? If all lists in the map were empty, return FALSE.</p>
  
  <pre><code>Map&lt; String , List&lt;String&gt; &gt; map = …
  </code></pre>
  
  <p>Can use of Streams replace this conventional code?</p>
  
  <pre><code>// See if any diffs were found. Loop through the Map, look at each List of diffs to see if non-empty.
  boolean anyElementsInAnyList = false;
  for (List&lt;String&gt; list : map.values () ) {
      if (!list.isEmpty()) {
          anyElementsInAnyList = true;
          break;
      }
  }
  </code></pre>
  
  <p>Note that we can break out of the examination after the first finding. No need to examine all the Map values (all the Lists). Would be nice if, for efficiency, the Stream could do the same stop-work-on-first-finding (a “short-circuiting” operation).</p>