Hello World In OAF:Controller Code

/**
 * Controller for ...
 */
public class HelloWorldCO extends OAControllerImpl
{
  public static final String RCS_ID="$Header$";
  public static final boolean RCS_ID_RECORDED =
        VersionInfo.recordClassVersion(RCS_ID, "%packagename%");

  /**
   * Layout and page setup logic for a region.
   * @param pageContext the current OA page context
   * @param webBean the web bean corresponding to the region
   */
  public void processRequest(OAPageContext pageContext, OAWebBean webBean)
  {
    super.processRequest(pageContext, webBean);
  }

  /**
   * Procedure to handle form submissions for form elements in
   * a region.
   * @param pageContext the current OA page context
   * @param webBean the web bean corresponding to the region
   */
  public void processFormRequest(OAPageContext pageContext, OAWebBean webBean)
  {
    super.processFormRequest(pageContext, webBean);
    if(pageContext.getParameter("GoBtn")!=null)
      {
       String userContent = pageContext.getParameter("HelloItem");
       String message ="Hello,"+userContent+"!";
       throw new OAException(message,OAException.INFORMATION);
      }
  }

}