B 树实现 - 我是否应该将 Node 类设为静态成员类？
我需要为大学实现一棵 B 树：
我有一个“外部”类 B 树，其属性为 root 和 _ Degree。表示节点的类被实现为静态成员类：
public class BTree<E> {
private Node<E> root;
// the minimal degree
private int degree;
public BTree(int degree) {
if (degree < 2) {
throw new IllegalArgumentException();
}
this.degree = degree;
}
// other stuff
private static class Node<T> {
T[] elements = (T[])new Object[degree * 2 - 1];
Node<T>[] children = (Node<T>[])new Object[degree * 2];
int size = 0;
}
}
所以，现在我的问题是： 当我将 Node 类实现为静态成员类时，我无法访问外部类的 Degree 属性。
现在我必须选择：
- 使 Node 类成为内部类（非静态成员类）或
- 为 Node 类创建一个构造函数，并在每次需要构造 Node 时传递度数。
最好的选择是什么？使其成为内部类意味着节点都将引用 Btree（外部类），但使其成为静态成员类意味着我每次都必须传递学位。
I need to implement a B-Tree for University:
I have an "outer" class B-Tree with attributes root and _degree. The class to represent the nodes is implemented as a static-member class:
public class BTree<E> {
private Node<E> root;
// the minimal degree
private int degree;
public BTree(int degree) {
if (degree < 2) {
throw new IllegalArgumentException();
}
this.degree = degree;
}
// other stuff
private static class Node<T> {
T[] elements = (T[])new Object[degree * 2 - 1];
Node<T>[] children = (Node<T>[])new Object[degree * 2];
int size = 0;
}
}
So, now my problem is: As I implemented the Node class as a static member class, I can't access the degree attribute of the outer class.
Now I have to choices:
- Make the Node class an inner class (non-static member class) OR
- Create a constructor for the Node class and pass the degree in every time I need to construct a Node.
What would be the best choice? Making it an inner class would mean the Nodes would all have a reference to the Btree (outer class), but making it a static member class would mean I would have to pass the degree in every time.
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我会将其保持静态并传递学位。这样您就可以确保
Node无法了解有关BTree的任何详细信息。I would keep it static and pass degree in. That way you ensure that
Nodecannot know any details aboutBTree.如果是我，我会将
Node类公开，这样我就可以在其他包含数据结构中重用它，但这只是我。在这种情况下，我必须通过构造函数传递学位，这对我来说也没关系。我不喜欢内部类操纵封闭类的成员的想法。我觉得这使得各个班级之间的联系过于紧密。我知道有时这是合适的，但我会尽可能避免，这似乎是一个很容易避免的情况。If it were me, I'd have the
Nodeclass public so I could reuse it in other containing data structures, but that's just me. In that case, I'd have to pass the degree through the constructor, and that's OK with me too. I don't like the idea of inner classes manipulating the members of enclosing classes. I feel it makes the classes too tightly bound to each other. I know sometimes it's appropriate, but I avoid when I can and this seems an easily avoidable case.有观点认为它是静态的，因为它解耦了类。
但我认为 BTree.Node 是特定 BTree 的节点。创建一堆节点（具有随机度数）是没有意义的。你不能有节点，但没有树。因此，我说非静态。
There are arguments to make it static, because it decouples the classes.
But I think a BTree.Node is a node from a particular BTree. It doesn't make sense to go and create a bunch of Nodes (with random degrees). You can't have a Node, but no Tree. Thus, I say non-static.