title: Java 8 sum and total not found
body: <p>EDIT: Found the solution here: <a href="http://www.dreamsyssoft.com/java-8-lambda-tutorial/map-reduce-tutorial.php">http://www.dreamsyssoft.com/java-8-lambda-tutorial/map-reduce-tutorial.php</a></p>
  
  <p>I'm following this tutorial:</p>
  
  <p><a href="http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/Lambda-QuickStart/index.html">http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/Lambda-QuickStart/index.html</a></p>
  
  <p>When I get to the part where it's using the sum and average functions, I get the following error:</p>
  
  <pre><code>UserAverageTest.java:68: error: cannot find symbol
          double average = users.parallelStream().filter(u -&gt; u.age &gt; 0).map(u -&gt; u.age).average().getAsDouble();
                                                                                        ^
    symbol:   method average()
    location: interface Stream&lt;Double&gt;
  </code></pre>
  
  <p>I get the same error when calling sum.  For some reason it appears that it's using the Stream instead of DoubleStream class.  I'm using the latest jdk with lambda enabled that is linked in the tutorial.</p>
  
  <p>Has anyone hit this issue as well and was able to resolve it?</p>
  
  <p>Here is a simple example that reproduces the problem:</p>
  
  <pre><code>class User {
      double age;
      public User(double age) { this.age = age; }
      double getAge() { return age; }
  }
  
  public static void main(String[] args) throws Exception {
      List&lt;User&gt; users = Arrays.asList(new User(10), new User(20), new User(30));
      double average = users.parallelStream()
                            .filter(u -&gt; u.age &gt; 0)
                            .map(u -&gt; u.age)
                            .average()
                            .getAsDouble();
  }
  </code></pre>