java - 我如何知道对象中存在哪些变量？

Question

我得到了这个代码:

//Class X is created, and then class Y is derived from class X:
class X
  {
  protected int m;
  }


class Y extends X
{
  private int n;
  public Y (int m, int n)
    {
     this.m = m;
     this.n = n;
    }
  public String toString ()
    {
     return m + ", " + n;
    }
}

//Class Y is used in the following way:
class UseY
{
  public static void main (String[] args)
  {
    Y y = new Y (3, 4);
    System.out.println (y);
  }
}

因此如您所见，代码涉及继承。

有人问我:

执行程序 UseY 时会创建哪个输出？对象 y 中存在哪些变量？

我的回答:

输出是: 3,4。 对象y中的变量是m和n。

但我不确定我的第二个答案。 变量到底是什么意思？我的回答正确吗？

Answer 1

我会说:

The object y has a nested member, called n and a derived member from its super-class, called m.