Java单向链表append方法实现指南

public class LinkedList {

    private Node head; // 链表的头节点

    // 内部类，表示链表中的一个节点
    private static class Node {
        int data; // 节点存储的数据
        Node next; // 指向下一个节点的引用

        public Node(int data) {
            this.data = data;
            this.next = null;
        }
    }

    // 向链表末尾添加元素的方法
    public void add(int data) {
        Node newNode = new Node(data);
        if (head == null) {
            head = newNode;
        } else {
            Node current = head;
            while (current.next != null) {
                current = current.next;
            }
            current.next = newNode;
        }
    }

    // 打印链表所有元素的方法
    public void printList() {
        Node current = head;
        while (current != null) {
            System.out.print(current.data + " -> ");
            current = current.next;
        }
        System.out.println("null");
    }

    /**
     * 将另一个链表追加到当前链表的末尾。
     *
     * @param otherList 要追加到当前链表末尾的链表。
     */
    public void append(LinkedList otherList) {
        // 1. 处理源链表为空的情况
        if (otherList == null || otherList.head == null) {
            // 如果otherList为空或otherList没有元素，则无需追加，直接返回
            return;
        }

        // 2. 处理当前链表（this）为空的情况
        if (this.head == null) {
            // 如果当前链表为空，则直接将otherList作为当前链表
            this.head = otherList.head;
            return;
        }

        // 3. 遍历当前链表，找到最后一个节点
        Node current = this.head;
        while (current.next != null) {
            current = current.next;
        }

        // 4. 将当前链表的最后一个节点的next指针指向otherList的头节点
        current.next = otherList.head;
    }

    public static void main(String[] args) {
        // 创建第一个链表
        LinkedList list1 = new LinkedList();
        list1.add(0);
        list1.add(1);
        list1.add(2);
        System.out.print("List1: ");
        list1.printList(); // 输出: List1: 0 -> 1 -> 2 -> null

        // 创建第二个链表
        LinkedList list2 = new LinkedList();
        list2.add(10);
        list2.add(11);
        System.out.print("List2: ");
        list2.printList(); // 输出: List2: 10 -> 11 -> null

        // 将list2追加到list1的末尾
        list1.append(list2);
        System.out.print("List1 after appending List2: ");
        list1.printList(); // 输出: List1 after appending List2: 0 -> 1 -> 2 -> 10 -> 11 -> null

        // 测试当前链表为空的情况
        LinkedList emptyList = new LinkedList();
        LinkedList singleNodeList = new LinkedList();
        singleNodeList.add(99);
        System.out.print("EmptyList: ");
        emptyList.printList();
        System.out.print("SingleNodeList: ");
        singleNodeList.printList();
        emptyList.append(singleNodeList);
        System.out.print("EmptyList after appending SingleNodeList: ");
        emptyList.printList(); // 输出: EmptyList after appending SingleNodeList: 99 -> null

        // 测试源链表为空的情况
        LinkedList list3 = new LinkedList();
        list3.add(100);
        LinkedList emptyOtherList = new LinkedList();
        System.out.print("List3: ");
        list3.printList();
        System.out.print("EmptyOtherList: ");
        emptyOtherList.printList();
        list3.append(emptyOtherList);
        System.out.print("List3 after appending EmptyOtherList: ");
        list3.printList(); // 输出: List3 after appending EmptyOtherList: 100 -> null
    }
}