multithreading - updating datagridview from within a thread causes error c# winform -

i writing c# winform uses datagridview object. @ point in program need update said datagridview within thread. causes program throw unhandled exception saying object reference not set instance of object, , makes datagridview turn error image of white box red x in it.

specifically trying in case update values in rows, removing rows , updating statistical values , reinserting rows.

i in separate function thread calls , updates 2 rows in datagridview every time.

here code update function:

private void updatestats(int binnumber)     {         binnumber *= 2;//has multiply 2 because every bin has 2 rows in table         if (statsdata.rows.count >= (binnumber + 1))         {             statsdata.rows.removeat(binnumber);             //number not change because index decreased 1             statsdata.rows.removeat(binnumber);//because every bin requires 2 rows         }         bin bin = bins[binnumber / 2];         list<double> realetempdata = new list<double>();         list<double> imagetempdata = new list<double>();         list<double> realalphatempdata = new list<double>();         list<double> imagalphatempdata = new list<double>();         //updates average , std dev values         foreach (minsearchdata datapoint in bin.bindata)         {             realetempdata.add(datapoint.reale);             imagetempdata.add(datapoint.image);             realalphatempdata.add(datapoint.realalpha);             imagalphatempdata.add(datapoint.imagalpha);         }         bin.averagereale = realetempdata.average();         bin.averageimage = imagetempdata.average();         bin.stddevreale = calculatestandarddeviation(realetempdata);         bin.stddevimage = calculatestandarddeviation(imagetempdata);         bin.averagerealalpha = realalphatempdata.average();         bin.averageimagalpha = imagalphatempdata.average();         bin.stddevrealalpha = calculatestandarddeviation(realalphatempdata);         bin.stddevimagalpha = calculatestandarddeviation(imagalphatempdata);         realetempdata.clear();         imagetempdata.clear();         realalphatempdata.clear();         imagalphatempdata.clear();         datarow myrow = statsdata.newrow();          myrow[0] = bin.binname;         myrow[1] = "real";         myrow[2] = bin.averagerealalpha;         myrow[3] = bin.stddevrealalpha;         myrow[4] = bin.averagereale;         myrow[5] = bin.stddevreale;         statsdata.rows.insertat(myrow, binnumber);          datarow myrow2 = statsdata.newrow();         myrow2[0] = "";         myrow2[1] = "imaginary";         myrow2[2] = bin.averageimagalpha;         myrow2[3] = bin.stddevimagalpha;         myrow2[4] = bin.averageimage;         myrow2[5] = bin.stddevimage;         statsdata.rows.insertat(myrow2, binnumber + 1);     } 

the stranger part of seem unable catch exception, , happens inconsistently, in sometime fails first time tries update, , other times fails on first try.

any appreciated,

thanks,

-jake

this may cause due race problem. in other words, 1 thread (likely main thread) tries paint grid based on current list of rows while other thread infers , manipulates it. moreover, guess have turned off checkforillegalcrossthreadcalls able manipulate grid directly on threads. if is, main cause of problem. anyway, possible solution use begininvoke indirectly work control:

private void updatestats(int binnumber) {   datagridview1.begininvoke(new methodinvoker(() =>   {         binnumber *= 2;//has multiply 2 because every bin has 2 rows in table         if (statsdata.rows.count >= (binnumber + 1))           ....           ....           ....                 myrow2[5] = bin.stddevimage;         statsdata.rows.insertat(myrow2, binnumber + 1);    } } 

edit:

i thought statsdata datagridview. based on op's comment datatable. so, tailored answer reflect fact.