如何在链表的末尾添加项?

Question

我正在为我的数据结构类做一个项目，这个项目要求我写一个类来实现一个int型的链表。

• 为Node使用内部类
• 包括以下方法。
• 编写一个测试器，让你可以用任何你想要的数据以任何顺序测试所有的方法。

我必须创建一个名为"public void addToBack(int item)"方法。此方法用于"将项添加到列表的末尾"。下面是这个方法的代码。当我执行这个方法时，我的列表变成空的。有人知道我做错了什么以及如何修复它吗?

import java.util.Random;
import java.util.Scanner;
public class LinkedListOfInts {
Node head;
Node tail;
private class Node {
int value;
Node nextNode;
public Node(int value, Node nextNode) {
this.value = value;
this.nextNode = nextNode;
}
}
public LinkedListOfInts(LinkedListOfInts other) {
Node tail = null;
for (Node n = other.head; n != null; n = n.nextNode) {
if (tail == null)
this.head = tail = new Node(n.value, null);
else {
tail.nextNode = new Node(n.value, null);
tail = tail.nextNode;
}
}
}
public LinkedListOfInts(int[] other) {
Node[] nodes = new Node[other.length];
for (int index = 0; index < other.length; index++) {
nodes[index] = new Node(other[index], null);
if (index > 0) {
nodes[index - 1].nextNode = nodes[index];
}
}
head = nodes[0];
}
public LinkedListOfInts(int N, int low, int high) {
Random random = new Random();
for (int i = 0; i < N; i++)
this.addToFront(random.nextInt(high - low) + low);
}
public void addToFront(int x) {
head = new Node(x, head);
}
public void addToBack(int x) {
if (head == null) {
head = new Node(x, head);
return;
}
tail = head;
while (tail.nextNode != null) {
tail = tail.nextNode;
}
tail.nextNode = new Node(x, tail);
}
public String toString() {
String result = "";
for (Node ptr = head; ptr != null; ptr = ptr.nextNode) {
if (!result.isEmpty()) {
result += ", ";
}
result += ptr.value;
}
return "[" + result + "]";
}
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
LinkedListOfInts list = new LinkedListOfInts(10, 1, 20);
boolean done = false;
while (!done) {
System.out.println("1. Add to Back");
System.out.println("2. toString");
switch (input.nextInt()) {
case 1:
System.out.println("Add an Item to the Back of a List.");
list.addToBack(input.nextInt());
break;
case 2:
System.out.println("toString");
System.out.println(list.toString());
break;
}
}
}
}

Answer 1

当您添加到tail时，nextNode应该指向null

tail.nextNode = new Node(x, null);

现在你有一个无限循环