java - 如何使用 Java 按字母顺序对链表进行排序？

Question

我正在做一个图书馆库存系统，所以我应该按字母顺序对 Node 中的名称进行排序。我有书名、作者、isbn 号、副本数和流派，所有这些信息我都存储在一个类中。

我确实为它编写了按字母顺序排序的代码，但它不起作用。 有人可以告诉我我的代码有什么问题吗？

这是我的链表类，包含插入和显示方法:

 public class LinkedList
{
Node node = new Node();
static Node head;

public LinkedList()
{
    head=null;
}

public Node getHead()
{
    return head;
}

public static void addNode(Data data)
{
     Node newNode = new Node(data, head);

    if (head == null) {
        head = newNode;
        newNode.setNext(null);
    } else {
        Node next = head;
        Node prev = next;
    do {
        if (data.name.compareTo(next.data.name) < 0) {
            break;
        }
        prev = next;
        next = next.getNext();
    } while (next != null);

    newNode.setNext(next);
    if (data.name.compareTo(next.data.name) < 0) {
        head = newNode;
    } else prev.setNext(newNode);
}
}

public static String displayNode()
{
    Node current = head;
    String output = "";
    while(current != null){       
        output+=current.data.toString();
        current = current.next;  
    }
    return output;
}

这是我的节点类:

public class Node 
{
Data data;
Node next;

public Node()
{
    next = null;
}

Node(Data data, Node next)
{
    this.data = data;
    this.next = next;
}

public Object getData()
{
    return data;
}

public Node getNext()
{
    return next;   
}

public void setNext(Node next)
{
    this.next=next;
}
}

这是我的数据类:

public class Data {
LinkedList list;
String name;
String author;
int isbn;
int number;
String genre;

public Data(String name, String author, int isbn, int number, String genre)
{
    this.name = name;
    this.author = author;
    this.isbn = isbn;
    this.number = number;
    this.genre = genre;
}

public String toString()
{
    return("Book Name: "+name+"\nAuthor: "+author+"\nISBN Number: "+isbn+"\nNumber of Copies: "+number+"\nGenre: "+genre+"\n\n");
}

public String getName()
{
    return name;
}

这是我用来显示列表的 Iterator 类:

public class DisplayIterator
{
LinkedList list;
static Node current;
static Node newNode;

DisplayIterator(Node newNode)
{
    this.newNode = newNode;
    current = list.head;
}

public static boolean hasNext()
{
    if(current == null){
        return false;
    }
    else if (current.next == null){
        return false;
    }
    return true;
}

public static Node next()
{
    if(hasNext()){
        current = current.next;
    }
    return current;
}

public static void remove(){
    throw new UnsupportedOperationException("It is read-only.");        
}

}

谢谢。

Answer 1

以下代码实现了对链表的基于顺序的插入。这当然假设列表已经排序。做出此假设是安全的，因为在您的界面中将节点添加到链表的唯一方法是通过此方法。

public static void addNode(Data data) {
    Node newNode = new Node(data, head);
    if (head == null) {
        head = newNode;
        return;
    }
    Node current = head;
    while (current.next != null && data.name.compareTo(current.data.name) >= 0) {
        current = current.next;
    }
    if (current == head && data.name.compareTo(current.data.name) < 0) {
        newNode.next = head;
        head = newNode;
    }
    else {
        newNode.next = current.next;
        current.next = newNode;
    }
    JOptionPane.showMessageDialog(null,"Book Information has been added to the inventory.");
}