将列表与Dart / Flutter中的值进行比较

Question

I am trying to compare an input value to a list of items in Dart language, however, it does not seem to work.

Method:

  String validateStoreNumber(String value) {

    List<String> storeList = ['55', '56', '88'];

    // String patttern = r'(^[a-zA-Z ]*$)';
    RegExp regExp = new RegExp(r'^[+-]?([0-9]+([.][0-9]*)?|[.][0-9]+)$');
    if (value.length == 0) {
      return "car number is required";
    } else if (!regExp.hasMatch(value)) {
      return "Accepts only numbers";
    } else if (value.length != 2){

      return "car number must have 2 digits";
    } else if (value != storeList.contains(value)){

      return "Not our model";
    }
    return null;
  }

Answer 1

This line...

else if (value != storeList.contains(value))

Is the problem. The left side "value" is a string, and the right side "contains" is a boolean. You are comparing a string to a boolean.

I think you want this...

else if (!storeList.contains(value))