在空的 LinkedList 中存储一个字符串值
public class LinkedListExplained {
public Node head;
public Node tail;
public int size;
public LinkedListExplained() { // Constructor
head = null;
tail = null;
size = 0;
}
public class Node{ // Inner Class
String value;
Node next;
}
public void add(String value){
Node node = new Node();
node.value = value;
size++;
if (head == null){
head = node;
tail = node;
return;
}
tail.next = node;
tail = node;
}
问题，当将单个 String 值存储到空 LinkedList 时，它是否会存储相同的值两次？ 一次是头，一次是尾？
public class LinkedListExplained {
public Node head;
public Node tail;
public int size;
public LinkedListExplained() { // Constructor
head = null;
tail = null;
size = 0;
}
public class Node{ // Inner Class
String value;
Node next;
}
public void add(String value){
Node node = new Node();
node.value = value;
size++;
if (head == null){
head = node;
tail = node;
return;
}
tail.next = node;
tail = node;
}
Question, when storing a single String value to an empty LinkedList, does it store the same value twice?
Once as head and once as tail?
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评论（2）
不会。
head和tail变量指向同一个Node对象。该对象包含一次String。No. The
headandtailvariables point to the sameNodeobject. That object contains theStringonce.如果你正在学习 Java，你首先需要了解的是，在 Java 中，所有看起来像对象的东西实际上都不是对象；相反，它是一个对象。它是一个指向对象的指针。当然，两个指针可能指向同一个对象。
因此，语句
public Node head;并未声明Node的实例。它声明了一个指向 Node 实例的指针。这就是为什么你必须稍后使用 new Node(); 的原因。因此，由于您将
head和tail指针都设置为指向Node的同一个实例，因此您可能有两个副本那个节点，但事实上你没有。您只有一个Node实例，并且有两个指向它的指针。If you are learning Java, the first and foremost thing you need to understand is that in Java, everything that looks like an object is never actually an object; it is a pointer to an object. And of course two pointers may point to the same object.
So, the statement
public Node head;does not declare an instance ofNode. It declares a pointer to an instance ofNode. That's why you have to usenew Node();later.So, since you set both the
headand thetailpointers to point to the same instance ofNode, it might appear that you have two copies of that node, but in fact you do not. You only have one instance ofNode, and you have two pointers pointing at it.