how to check string contains only integer in dart code example

Example 1: flutter check if string is number dart

bool isNumeric(String s) {
 if (s == null) {
   return false;
 }
 return double.tryParse(s) != null;
}

Example 2: check only digits in dart

bool isNumeric(String s) {
 if (s == null) {
   return false;
 }
 return double.tryParse(s) != null;
}