title: Exception starting filter struts2 java.lang.NullPointerException?
body: <p>The error "Exception starting filter struts2 java.lang.NullPointerException" is shown when i Try to run my application. I am programming in Eclipse 3.6 on Struts 2. part of my My Struts.xml looks like below: </p>
  
  <pre><code>   &lt;struts&gt;
      &lt;!-- remove these constant elements in production --&gt;
      &lt;constant name="struts.enable.DynamicMethodInvocation" value="false" /&gt;
      &lt;constant name="struts.devMode" value="true" /&gt;
      &lt;package name="app02a" extends="struts-default"&gt;
          &lt;action name="Product_input"&gt;
              &lt;result&gt;/jsp/Product.jsp&lt;/result&gt;
          &lt;/action&gt;
          &lt;action name="Product_save" class="app02a.Product" method="execute"&gt;
              &lt;result&gt;/jsp/Details.jsp&lt;/result&gt;
          &lt;/action&gt;
      &lt;/package&gt;
  
  &lt;/struts&gt;
  </code></pre>