title: Java 8 Map: filter value and throw exception if match found
body: <p>I'm trying to find a matching value in a Map and if found, I need to throw an IllegalArgumentException. My code is as follows:</p>
  
  <pre><code>final String stringToBeMatched = "someRandomString"; 
  
  map.values()
     .stream()
     .filter(a -&gt; stringToBeMatched == a.getField())
     .findAny()
     .ifPresent(a -&gt; throw new IllegalArgumentException());
  </code></pre>
  
  <p>I get a syntax error on token "throw". I'm not sure where I'm going wrong. </p>