Dart language snippit

main.dart

void main() {
  
  /// maps
  /// result:
  ///   map0: {1: 1, 2: 2}
  ///   map1: {1: 1, 2: 2}
  ///   map2: {1: 2, 2: 3}
  Map<String, int> map = {'1' : 1, '2' : 2};
  print('map0: $map');

  final map2 = map.map((a, value) {
        return MapEntry<String, String>(a, (++value).toString());
      }
    );

  print('map1: $map');
  print('map2: $map2');
  
  
  /// datetime to string converter
  /// result:
  ///   2018-09-11T16:57:15.873Z
  ///   2018-09-11 16:53:21.021Z
  DateTime stringToDateTime(String s) => DateTime.parse(s);
	String timeToString(DateTime t) => t.toUtc().toIso8601String();
  
  final now = DateTime.now();
  print(timeToString(now));
  
  final str = '2018-09-11T16:53:21.021Z';
  print(stringToDateTime(str).toString());
}

main2.dart

void main(){
	List a = [A, B];
	print(a.runtimeType);		// List<dynamic>
	print(a[0].runtimeType);	// _Type

	List b = EnumTypes;

	// b: List<dynamic> b[0]: _Type b[1]: _Type
	print("runtimeType:  b: ${b.runtimeType} b[0]: ${b[0].runtimeType} b[1]: ${b[1].runtimeType}");

	E1 e1 = E1.a;
	print(e1 is E1); // true

	final e1Str = 'a';

	// T is in EnumTypes list: true
	// str2Enum('a'): null
	print("str2Enum('a'): ${str2Enum<E1>(e1Str)}");



}


const List EnumTypes = [E1, E2];
class A{}
class B{}

enum E1{
	a, b, c
}

enum E2{
	d, e, f
}


enum E3{
	g, h, i
}

T str2Enum<T>(String s) {
	print("T is in EnumTypes list: ${EnumTypes.contains(T)}");
	
	final type = EnumTypes.firstWhere((t) {
		
      	final result = t == T;
      	print("checking t: $t, T: $T, (=)?: $result");
      	return result;
    });
	// final same = $type==$T;
    print("type:$type, T:$T, type=T? ${type == T}, type.runtimeType:${type.runtimeType}");

    var result;
    try {
    		result = T.values.firstWhere((x) => x.toString().toLowerCase() == "$T.$s".toLowerCase());
    		print("result: $result");
    	} catch (e) {
    		print("error: $e");
    	}
    


	return result;
}

run it your self at dartpad

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