如下代码运行结果为：
class Test {
public static void main(String[] args) {
A a = new B();
System.out.println(a.method());
}
}
class A{
public A() {
System.out.println("A");
}
public String method(){
return "a";
}
}
class B extends A{
public B() {
System.out.println("B");
}
@Override
public String method() {
return "b";
}
}
