Inheritance About Mixin and Class Dart - dart

Question

Please look the code ,i want to know
1.who is C super
2.in the class C ,when i call 'super.method()', Mixin excute 'void method()'(so C's super is Mixin?), then, when excute 'super.method()', B excute 'void method()'(so C's super is B?),why?
It's running Dart 2.1.2
void main() {
C().printSuper();
C().method();
}
abstract class A {
void method() {
print("A");
}
}
class B implements A {
#override
void method() {
print("B");
}
}
mixin Mixin on A {
#override
void method() {
super.method();
print("mixin");
}
}
class C extends B with Mixin {
void printSuper() {
super.method();
}
}
print message:
I/flutter (21340): B
I/flutter (21340): mixin
I/flutter (21340): B
I/flutter (21340): mixin
i expected the output print message:
I/flutter (21340): B
I/flutter (21340): B
I/flutter (21340): mixin

Answer 1

The superclass of C is B with Mixin, which is an anonymous class introduced by the extends B with Mixin clause.
The class C is equivalent to a class declared as follows:
class _BwithMixin extends B implements Mixin {
void method() {
super.method();
print("mixin");
}
}
class C extends _BwithMixin {
void printSuper() {
super.method();
}
}
So, the printSuper doesn't directly hit the method of B, it hits the method of the superclass of C which is B with Mixin, and that method is the one copied from Mixin. It will then call super.method() from _BwithMixin, and the superclass of that is B, so it will first print mixin and then B.