The code is crashing while removing column from AdvancedDataGrid.

[santusapi]

Hello All,
I am facing problem while removing the columns from
AdvancedDataGrid. It is crashing at one point and i am unable to
resolve it.

The code i'm using to remove the columns is like this.

               public function clearPlot():void
               {
                       cols = cols.slice(0, 0);
 
                       this.columns = cols;
                       this.validateNow();
               }
 

The class is extending AdvancedDataGrid and the variable "cols" is an
Array type. And also i have tried many variations, but none of
them solved the problem. So i'm giving the variations also.

[1]

               public function clearPlot():void
               {
                       cols = cols.slice(0, 0);
                       cols.push(new AdvancedDataGridColumn(""));
 
                       this.columns = cols;
                       this.validateNow();
               }
 

[2]

             public function clearPlot():void
               {
                       cols = new Array();
                       cols.push(new AdvancedDataGridColumn("dummy"));
 
                       this.columns = cols;
                       this.validateNow();
               }
 

[3]

             public function clearPlot():void
               {
                       cols = new Array();
 
                       this.columns = cols;
                       this.validateNow();
               }
 

[4]

             public function clearPlot():void
               {
                       this.columns = null;
                       this.validateNow();
               }
 

[5]

             public function clearPlot():void
               {
                       cols = null;
                       cols = new Array();
 
                       this.columns = cols;
                       this.validateNow();
               }
 

The error is like this:

TypeError: Error #1009: Cannot access a property or method of a null
object reference.
at mx.controls::AdvancedDataGridBaseEx/http://www.adobe.com/2006/flex/
mx/internal::getHeaderInfo()[C:\work\flex\dmv_automation\projects
\datavisualisation\src\mx\controls\AdvancedDataGri dBaseEx.as:2366]
at mx.controls::AdvancedDataGrid/http://www.adobe.com/2006/flex/mx/
internal::getHeaderInfo()[C:\work\flex\dmv_automation\projects
\datavisualisation\src\mx\controls\AdvancedDataGri d.as:2147]
at mx.controls::AdvancedDataGrid/getFieldSortInfo()[C:\work\flex
\dmv_automation\projects\datavisualisation\src\mx\ controls
\AdvancedDataGrid.as:6840]
at
mx.controls.advancedDataGridClasses::AdvancedDataG ridHeaderRenderer/
getFieldSortInfo()[C:\work\flex\dmv_automation\projects
\datavisualisation\src\mx\controls\advancedDataGri dClasses
\AdvancedDataGridHeaderRenderer.as:757]
at
mx.controls.advancedDataGridClasses::AdvancedDataG ridHeaderRenderer/
updateDisplayList()[C:\work\flex\dmv_automation\projects
\datavisualisation\src\mx\controls\advancedDataGri dClasses
\AdvancedDataGridHeaderRenderer.as:560]
at mx.core::UIComponent/validateDisplayList()[C:\autobuild
\3.3.0\frameworks\projects\framework\src\mx\core\U IComponent.as:6351]
at mx.managers::LayoutManager/validateDisplayList()[C:\autobuild
\3.3.0\frameworks\projects\framework\src\mx\manage rs\LayoutManager.as:
622]
at mx.managers::LayoutManager/doPhasedInstantiation()[C:\autobuild
\3.3.0\frameworks\projects\framework\src\mx\manage rs\LayoutManager.as:
695]
at Function/http://adobe.com/AS3/2006/builtin::apply()
at mx.core::UIComponent/callLaterDispatcher2()[C:\autobuild
\3.3.0\frameworks\projects\framework\src\mx\core\U IComponent.as:8628]
at mx.core::UIComponent/callLaterDispatcher()[C:\autobuild
\3.3.0\frameworks\projects\framework\src\mx\core\U IComponent.as:8568]


And i'm giving the stack trace also. It is:
mx.controls::AdvancedDataGridBaseEx/http://www.adobe.com/2006/flex/mx/
internal::getHeaderInfo
mx.controls::AdvancedDataGrid/http://www.adobe.com/2006/flex/mx/
internal::getHeaderInfo
mx.controls::AdvancedDataGrid/getFieldSortInfo
mx.controls.advancedDataGridClasses::AdvancedDataG ridHeaderRenderer/
getFieldSortInfo
mx.controls.advancedDataGridClasses::AdvancedDataG ridHeaderRenderer/
updateDisplayList
mx.core::UIComponent/validateDisplayList
mx.managers::LayoutManager/validateDisplayList
mx.managers::LayoutManager/doPhasedInstantiation
Function/http://adobe.com/AS3/2006/builtin::apply [no source]
mx.core::UIComponent/callLaterDispatcher2
mx.core::UIComponent/callLaterDispatcher


Please help me in solving this.