如何在dart中将数据从实用程序类传递到主类

class UtilityClass {
  String data;

  UtilityClass(this.data);
}

class MainClass {
  UtilityClass utility;

  MainClass(this.utility);
}

void main() {
  UtilityClass utility = UtilityClass("Hello");
  MainClass main = MainClass(utility);

  print(main.utility.data); // 输出：Hello
}

class UtilityClass {
  String data;
}

class MainClass {
  UtilityClass _utility;

  set utility(UtilityClass utility) {
    _utility = utility;
  }

  void printData() {
    print(_utility.data);
  }
}

void main() {
  UtilityClass utility = UtilityClass();
  utility.data = "Hello";

  MainClass main = MainClass();
  main.utility = utility;

  main.printData(); // 输出：Hello
}

class UtilityClass {
  String data;

  static UtilityClass getInstance(String data) {
    UtilityClass utility = UtilityClass();
    utility.data = data;
    return utility;
  }
}

class MainClass {
  UtilityClass utility;

  MainClass(this.utility);
}

void main() {
  UtilityClass utility = UtilityClass.getInstance("Hello");
  MainClass main = MainClass(utility);

  print(main.utility.data); // 输出：Hello
}