class Go extends A {
public static void main(String[] args) {
new Go().start();
}
private void start() {
check(new A(), new Go());
check((Go)new A(), new Go());
}
private void check(A a, A a1) {
Go go = (Go) a; // 1
A a2 = (A) a1; // 2
}
}
class A{
}