Person p1 = new Person();
p2.say();
p1.say();
p2=null;
p2.say();
}
}
下列选项中描述正确的是（）。

public static void main(String[] args) {

B b = new B();

b.test();

}

void test() {

System.out.print("A");

}

}

class B extends A {

void test() {

super.test();

System.out.print("B");

}

}

class Dog {

String name;

Dog(String name) {

this.name = name;

}

}

public class Demo1 {

public static void main(String[] args) {

Dog dog1 = new Dog("xiaohuang");

Dog dog2 = new Dog("xiaohuang");

String s1 = dog1.toString();

String s2 = dog2.toString();

String s3 = "xiaohuang";

String s4 = "xiaohuang";

}

}