在子类中调用父类对象指向的变量，这段代码中parent.count调用的是哪个类的count？为什么？

public class ChildClass extends ParentClass{
    public float count;
    public ChildClass()
    {
        System.out.println("This is ChildClass");
        count=0;
    }
    public int add()
    {
        return sum;
    }
    public int add(int i)
    {
        return sum+=i;
    }
    public static void main(String arg[])
    {
        ParentClass parent=new ParentClass();
        ChildClass child=new ChildClass();
        parent=child;
        System.out.println(parent.add());
        System.out.println("parent.count="+parent.count);
        System.out.println(child.add(100));
        System.out.println("child.sum="+child.sum);
    }
}

class ParentClass{
    protected int sum;
    protected int count;
    public ParentClass()
    {
        System.out.println("This is ParentClass");
        count=20;
        sum=10;
    }
    public int add()
    {
        for(int i=1;i<=100;i++)
        {
            sum++;
        }
        return sum;
    }
}

ChildClass child=new ChildClass();
parent=child;
所以调用的是child的