when concatenate null value to a string , it shows error how to solve this problem, please help

[Navas jaseer]

hi,

i have getting the error when am concatenting two strings , how to solve this problem 

here below the error message shows in console

"Unhandled Exception: Invalid argument(s) _StringBase.+ (dart:core-patch/string_patch.dart:267:57)"

regards,

navas jaseer

[sow...@csdcorp.com]

You can use the ?? operator to provide a default, like so:

var str3 = (str1 ?? '') + (str2 ?? '');