how to use hexadecimal color in flutter

Color c = const Color(0xFF42A5F5);
Color c = const Color.fromARGB(0xFF, 0x42, 0xA5, 0xF5);
Color c = const Color.fromARGB(255, 66, 165, 245);
Color c = const Color.fromRGBO(66, 165, 245, 1.0);

const color = const Color(0xffb74093); // Second `const` is optional in assignments.

Color myHexColor = Color(0xff123456) 

// her you notice I use the 0xff and that is opacity or transparency of the color 
// and you can also change these value .