a.dart
part of sum; class A { static int a = 10; }
b.dart
part of sum; class B { static int b = 100; }
sum.dart
//定义一个库 library sum; //声明两个文件属于sum库 part './a.dart'; part './b.dart'; int s() { return A.a + B.b; }
main.dart
import './lib/sum.dart'; main(List<String> args) { print(s()); }