Question

public class A {
    public A() {
        System.out.println("A1");
    }
    public A(int a) {
        System.out.println(a);
    }
    public int foo(int a) {
        return 0;
    }
}
public class AA extends A {
    public AA(int aa) {
        System.out.println(aa);
    }
}
public class B extends A {
    public B(int b) {
        super(b);
    }
    public int foo(Integer b) {
        b = new Integer(b + 5);
        return b;
    }
    public int foo(int b) {
        return b;
    }
}
public class C {
    public static void main(String[] args) {
        B b = new B(5);
        A a = (A) b;
        System.out.println(a.foo(2));
    }
}