title: NetBeans : diamond operator is not supported in -source 1.5 (use -source 7 or higher to enable diamond operator)
body: <p>I don't know why when I code:</p>
  
  <pre><code>List&lt;String&gt; data = new ArrayList&lt;&gt;();
  </code></pre>
  
  <p>it said that </p>
  
  <pre>
  diamond operator is not supported in -source 1.5
    (use -source 7 or higher to enable diamond operator)
  ----
  (Alt-Enter shows hints)
  </pre>
  
  <p>I already use JDK 1.7. When I opened it in eclipse, I didn't get that error.</p>