为什么这里打印出来的name属性的值为null呢,求大佬告知,还有setName方法中的this不是指代pig对象吗,为this.name却赋值给了Animal的name属性,这其中有什么原因呢

class Animal{
String name = “物种”;
Animal(String name){
this.name = name;
}
public Animal() {
}
public void setName(String name){
this.name = name;
}
public String getName(){
return this.name;
}
}

class Pig extends Animal{
String name;
Pig(String name){
super(name);
}
public String toString(){
return name;
}
}

public class B{
public static void main(String[] args) {
Pig pig = new Pig(“小猪”); //如果这里用多态的写法,把Pig换成Animal,下边就打印渣渣,这是为啥呢??
pig.setName(“渣渣”);
System.out.println(pig.name);