JTable 没有填充正确的信息

Question

我正在从树形图中填充我的表，并且树形图正在从我的 sql 数据库中填充，错误是数据在我的表中出现的顺序。 我已经发布了一个截图给你看。

这是我的 sql 中的图像

public class LibraryData {

    private Connection con;
    private Statement stmt;
    private ResultSet res;

    public LibraryData() {
        try {

            // con = DriverManager.getConnection("jdbc:mysql://;localhost:3306")
            String connectionUrl = "jdbc:sqlserver://SQL-SERVER;" + "databaseName=oe323;integratedSecurity=true;";
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
            con = DriverManager.getConnection(connectionUrl);
        } catch (Exception ex) {
            System.out.println("Erro: " + ex);

        }
    }

    public String listAll1() {
        String output = "";
        try {
            stmt = con.createStatement();
            res = stmt.executeQuery("SELECT * FROM LibraryTable");

            while (res.next()) { // there is a result
                // the name field is the thrid one in the ResultSet
                // Note that with  ResultSet we count the fields starting from 1
                output += res.getString(1) + " " + res.getString(2) + " - "
                        + res.getString(3) + " " + res.getString(4) + " "
                        + res.getString(5) + "\n";
                System.out.println(output);
                library.put("" + res.getInt(1), new Item(res.getString(2), res.getString(3), Integer.parseInt(res.getString(4))));



            }
        } catch (Exception e) {
            System.out.println(e);
            return null;
        }
        return output;
    }

    public static class Item {

        Item(String n, String a, int r) {
            name = n;
            artist = a;
            rating = r;
        }
        // instance variables 
        private String name;
        private String artist;
        private int rating;
        private int playCount;

        public String toString() {
            return name + " - " + artist;
        }
    }
    private static Map<String, Item> library = new TreeMap<String, Item>();
//

    static {

    }

    public static String listAll() {
        String output = "";
        Iterator iterator = library.keySet().iterator();
        while (iterator.hasNext()) {
            String key = (String) iterator.next();
            Item item = library.get(key);
            output += key + " " + item.name + " - " + item.artist + "\n";


        }
        return output;
    }

    public static void fillTable() {
        Iterator iterator = LibraryData.library.keySet().iterator();
        while (iterator.hasNext()) {
            String key = (String) iterator.next();
            LibraryData.Item item = LibraryData.library.get(key);

            DeleteSong.data = new Object[1][3];

            DeleteSong.data[0][0] = key;
            DeleteSong.data[0][1] = item.artist;

            DeleteSong.data[0][2] = item.name;
            DeleteSong.modeltable.addRow(DeleteSong.data[0]);


        }

    }

    public static void fillTable1() {
        // listAll1();
        Iterator iterator = LibraryData.library.keySet().iterator();
        while (iterator.hasNext()) {
            String key = (String) iterator.next();
            LibraryData.Item item = LibraryData.library.get(key);

            CheckLibrary.data = new Object[1][4];

            CheckLibrary.data[0][0] = key;
            CheckLibrary.data[0][1] = item.artist;

            CheckLibrary.data[0][2] = item.name;
            CheckLibrary.modeltable.addRow(CheckLibrary.data[0]);

            CheckLibrary.data[0][3] = item.rating;

Answer 1

问题是您的键实际上是数字，您希望按数字顺序对它们进行排序，但您的 library 键是 Strings，它们按字典顺序排序，例如， 1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2, 20, ...（就像 a,aa,ab,ac,广告，b，ba，bb，bc，...）。这种顺序在您的屏幕截图中很明显。

这是因为，出于某种原因，您决定在放入库映射时将整数键转换为字符串：

private static Map<String, Item> library = new TreeMap<String, Item>();
... 
// in listAll1() and elsewhere:
library.put("" + res.getInt(1), ...

您应该使用适合您所存储信息的数据类型。如果您的键是整数，请使用整数，例如：

private static Map<Integer, Item> library = new TreeMap<Integer, Item>();
...
// in listAll1() and elsewhere:
library.put(res.getInt(1), ...

您有一个显示此内容的屏幕截图，但没有代码。然后您添加了代码，但删除了屏幕截图。我将屏幕截图添加回您的问题。以后，请尝试发布与您遇到的问题直接相关的代码和信息。