Flutter implements callback

sample code

new interface class:

// sample class

class S {
  void Function(String)? onABC;
  void Function(int)? onDEF;

  STTCallback({this.onABC, this.onDEF});
}

how to use:

mian()  {

final st = S(onABC: (string) {
        print("S onABC: $string");
        // add here
    }, onDEF: (i) {
        print("S onDEF: $i");
        // add here
    }
}