Bug 173836 NPE was thrown when click "Preview " button quickly twice[00]
NPE was thrown when click "Preview " button quickly twice[00] Build number: 2.2.0.v20070212-0630 Steps to reproduce: 1.open attached report 2.click "Preview" button quickly twice Expected result: Report can be previewed properly Actual result: NPE was thrown in second preview Error log: see screen shot
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/context/ViewerAttributeBean.java
if ( curName != null
						&& curName.equalsIgnoreCase( configVarName ) )
				{
					paramName = parameter.getName( );
					break;
				}
			}
		}
		return paramName;
	}
	/**
	 * Returns the report design handle
	 * 
	 * @param request
	 * @throws Exception
	 * @return Report Design Handle
	 */
	protected IViewerReportDesignHandle getDesignHandle(
			HttpServletRequest request ) throws Exception
	{
		IViewerReportDesignHandle design = null;
		IReportRunnable reportRunnable = null;
		IReportDocument reportDocumentInstance = null;
		boolean isDocumentExist = ParameterAccessor.isReportParameterExist(
				request, ParameterAccessor.PARAM_REPORT_DOCUMENT );
		boolean isReportExist = ParameterAccessor.isReportParameterExist(
				request, ParameterAccessor.PARAM_REPORT );
		
		if ( isDocumentExist && !isReportExist )
		{