title: Cannot resolve symbol (Java 8) lambdas
body: <p>I'm kinda new to lambdas in Java 8.
  Here is a short snippet of my code:</p>
  
  <pre><code>public void analyzeQueries() {
    while (queries.size() &gt; 0) {
      int rating;
      InvestmentQuery query = getFirstPriority(queries);
      RatingCacheElement cacheElement = stockToRating.get(x -&gt; x.stockID == query.stockID);
  
      if (cacheElement != null)
        rating = cacheElement.rating;
      else {
        rating = calculateRating(query.stockID);
        stockToRating.add(new RatingCacheElement(query.stockID, rating));
      }
      if (rating &gt; 80)
        stockTrader.enqueueStock(query);
    }
  }
  </code></pre>
  
  <p>The complier output says "Error:(23, 54) java: incompatible types: int is not a functional interface".
  <code>x.stockID</code> is also being flagged with "Cannot resolve symbol".
  Using Android Studio 2.3.3, Gradle 1.14.1.</p>