java多态的应用 - Java / Java SE

interface animal{
  void sayHi();
  String getName();
}

class dog implements animal{
  public void sayHi(){
  System.out.println("I am "+getName()+bark());
  }
  public String bark(){
  return "wang-wang";
  }
  public String getName(){
  return "Bob.";
  }
}

class bulldog extends dog{
  public String getName(){
  return "Mike.";
  }
  public String bark(){
  return "wow-wow";
  }
}

public class test2{
  public static void main(String args[]){
  animal b=new bulldog();
  dog d=(dog)b; //A
  check(d);
  dog dd=(bulldog)b; //B
  check(dd);
  }
  public static void check(dog d){
  System.out.println("I am "+d.getName());
  }
  public static void check(bulldog d){
  System.out.println("I am "+d.getName());
  }
}
//A和B处怎么理解的阿？B处dog dd=(bulldog)b;是父类dog引用指向子类对象bulldog吗？A处理解成将一只公狗强制转换成一只狗？然后调用check(dog d)方法,d.getName();怎么还是调用公狗的getName()方法？
要晕了啊...
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