Expected a value of type 'string' but got one of type 'int'

I have a function that returns a String, but when I call this function, the app screen goes red and I get this error: Expected a value of type 'string' but got one of type 'int'.

Here is my function that returns a String:

  checkProportion(String predominantGamete, String resultado) {
    var countBrown = 0;
    var countBlack = 0;
    var countWhite = 0;
    var proportionCamundongo =
        'Proporção: ${countBrown}:${countBlack}:${countWhite}';

    if (predominantGamete == 'recessiva_aa' &&
        resultado.contains('A') &&
        resultado.contains('P')) {
      return countBrown  = 1;
    } else if (predominantGamete == 'recessiva_aa' &&
        resultado.contains('A') &&
        resultado.contains('pp')) {
      return countBlack  = 1;
    } else if (predominantGamete == 'recessiva_aa' &&
        resultado.contains('aa')) {
      return countWhite  = 1;
    }
    return proportionCamundongo;
  }

Here is how I call the function:

@override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.transparent,
        elevation: 0,
        title: Text(
          checkProportion(widget.predominant, widget.result),
        ),
      ),

How to solve this error?

Here is an image that shows the colors of each result:

CodePudding user response：

The issue here is that you are returning early, not breaking the if statement, when you do something like return countBrown = 1;;

Try incrementing the counters, then using string interpolation to display the value:

String checkProportion(String predominantGamete, String resultado) {
  int countBrown = 0;
  int countBlack = 0;
  int countWhite = 0;

  if (predominantGamete == 'recessiva_aa' &&
    resultado.contains('A') &&
    resultado.contains('P')) {
    countBrown  = 1;
  } else if (predominantGamete == 'recessiva_aa' &&
    resultado.contains('A') &&
    resultado.contains('pp')) {
    countBlack  = 1;
  } else if (predominantGamete == 'recessiva_aa' &&
    resultado.contains('aa')) {
    countWhite  = 1;
  }
  return 'Proporção: ${countBrown}:${countBlack}:${countWhite}';
}

I'd also recommend specifing the return type of the function (String), using the correct types for counters (int). That will help your compiler catch the issues as well.

CodePudding user response：

It isn't my best work, and there is probably a better way to check for if a string contains all occurrence of multiple substrings, but here you go:

bool isColorContained(String resultado, Set<String> requirements) {
  for(String requirement in requirements) {
      if (!resultado.contains(requirement)) {
        return false;            
      }
    }
  return true;
}

String checkProportion(String predominantGamete, String resultado) {         
  Map<ColorType, Set<String>> colorType = {
    ColorType.brown: {'A', 'P'},
    ColorType.black: {'A', 'pp'},
    ColorType.white: {'aa'},
  };
  Map<ColorType, int> colorTypeCount = {
    ColorType.brown: 0,
    ColorType.black: 0,
    ColorType.white: 0,
  };
  for(MapEntry<ColorType, Set<String>> entry in colorType.entries )  {
    if(predominantGamete != 'recessiva_aa') continue;
    bool contained = isColorContained(resultado, entry.value);        
    if(contained) {
      int count = colorTypeCount[entry.key] ?? 0;
      colorTypeCount[entry.key] = count   1;
    }      
  }
  return 'Proporção: ${colorTypeCount[ColorType.brown]}:${colorTypeCount[ColorType.black]}:${colorTypeCount[ColorType.white]}';
}

Also, declare the ColorType enum:

enum ColorType {
  brown, black, white
}

This will scale with as many colors and requirements you have, by adding to the ColorType enum, the colorType map, and the colorTypeCount map.