import'dart:html';
int i = 100;
String str = "sum is ";
int n = 110;
void main() {
A a = new A();
a.sum();
}
void btnClick(MouseEvent e){
window.alert("HelloDart");
}
class A{
int sum(){
window.alert((i + n).toString());
}
}
这货和Java一样, 就不解释了.