null - NullReferenceException was unhandles using Windows Forms c# -

i getting exception

nullreferenceexception unhandled

i have tried , tried again solve hours later , i'm coming here help.

this i'm getting error:

form1 objectform1 = new form1(); (int = 0; < 1; i++) {     objectform1.taskbox.items.add(        objectform1.taskitems[i].taskname +         objectform1.taskitems[i].taskdescription +         objectform1.taskitems[i].taskpriority +         objectform1.taskitems[i].taskduedate +         objectform1.taskitems[i].taskcompletion); } 

i know it's not lot work above, here other section of code, trying create object references instead of using lists etc, these items meant show in listbox:

using system; using system.collections.generic; using system.componentmodel; using system.data; using system.drawing; using system.linq; using system.text; using system.threading.tasks; using system.windows.forms;  namespace programming_and_data_structures_todolist {     public partial class form1 : form     {         public objectfile[] taskitems = new objectfile[10];         public form1()         {             initializecomponent();         }          public void formmain()         {             //creating form links----|             form2 objectform2 = new form2();             form1 objectform1 = new form1();             //---------------------------|              //above creating object reference             //below setting values             string taskname = objectform2.tasknamebox.text;             string taskdescription = objectform2.taskdescbox.text;             decimal taskpriority = objectform2.priorityupdown.value;             string taskduedate = objectform2.datetimepicker.value.toshortdatestring();             string taskcompletion = objectform2.completion;              (int = 0; < 1; i++)             {                 taskitems[i] = new objectfile(convert.tostring(taskname), convert.tostring(taskdescription), convert.toint32(taskpriority), convert.tostring(taskduedate), taskcompletion);             }         }          private void newtoolstripmenuitem_click(object sender, eventargs e)         {             form2 form2object = new form2(); //creates object link form2              form2object.showdialog(); //shows form2 (task input menu)         }          private void edittoolstripmenuitem_click(object sender, eventargs e)         {             environment.exit(0); //exits whole application         }          public void optionstoolstripmenuitem_click(object sender, eventargs e)         {         }     }     //object class     public class objectfile     {         public string taskname { get; set; }         public string taskdescription { get; set; }         public decimal taskpriority { get; set; }         public string taskduedate { get; set; }         public string taskcompletion { get; set; }          public objectfile(string taskname, string taskdescription, decimal taskpriority, string taskduedate, string taskcompletion)          {             taskname = taskname;             taskdescription = taskdescription;             taskpriority = taskpriority;             taskduedate = taskduedate;             taskcompletion = taskcompletion;         }     } } 

you setup taskitems in formmain, there no call method in code fails.

possible fix - call method

form1 objectform1 = new form1(); objectform1.formmain(); (int = 0; < 1; i++) .... 

for standard steps investigate nre check out what nullreferenceexception, , how fix it?