validate method
Implementation
void validate(String? newValue) {
final String? _newValue = newValue;
if (_newValue == null || _newValue.isEmpty) {
if (isRequired) {
throw RequiredValueException();
} else {
return;
}
}
late T? _decimal;
try {
_decimal = doParse(_newValue);
if (_decimal == null) {
throw RequiredValueException();
}
} catch (e) {
throw InvalidValueException();
}
}