// int to String
int j = 45;
String t = "$j";
//Use toString and/or toRadixString
int intValue = 1;
String stringValue = intValue.toString();
String hexValue = intValue.toRadixString(16);
// or
String anotherValue = 'the value is $intValue';
//String to int
String s = "45";
int i = int.parse(s);