java中多态中向下转型的问题

Question

public class Father {
public void show (){
System.out.println("父类方法");
}
public void show1(){
System.out.println("父类二方法");
}
}
public class Son extends Father {
public void show(){
System.out.println("子类方法");
}
public void show2(){
System.out.println("子类2方法");
}
}

public static void main(String[] args) {
// TODO Auto-generated method stub
Father son=new Son();
son.show();
son.show1();
Son son1=(Son) son;
son1.show();
son1.show1();
son1.show2();
}

    为什么son1.show1()  也会出现，该怎么理解？

Answer 1

Son 继承了Father中show1方法啊，所以son1.show1();会出现