Java TableView内容未显示

我有一个用信息填充的表视图，但是虽然我可以选择保存数据的行，但文本不可见。使用

table.getSelectionModel（）.getSelectedItem（）我可以确认表中确实包含元素，但文本没有显示

我的程序中有一个套接字通信，其中服务器向客户端发送客户端需要在TableView中显示的元素的ArrayList

服务器端：

private void acceptedConnection(Socket client, Connection con){
    try(ObjectInputStream ois = new ObjectInputStream(client.getInputStream());
        ObjectOutputStream oos = new ObjectOutputStream(client.getOutputStream())){
        System.out.println("receiving request");

        String table = ois.readUTF();

        System.out.println("Preparing statement");
        PreparedStatement getTableContent = con.prepareStatement("SELECT * from " + table);

        System.out.println("Fetching results");
        ResultSet tableContentRs = getTableContent.executeQuery();

        Builder builder = null;

        switch (table){
            case "blog_user": builder = new UserBuilder();break;
        }

        assert builder != null;
        ArrayList tableContent = builder.buildArrayList(tableContentRs);


        System.out.println("Sending results");
        oos.writeObject(tableContent);
        oos.flush();
        System.out.println("Results sent");
    }catch (IOException | SQLException e){
        e.printStackTrace();
    } finally {
        try {
            client.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

客户端：

public void loadTableContent(){
    try (Socket client = new Socket(InetAddress.getLocalHost(), 667);
         ObjectOutputStream oos = new ObjectOutputStream(client.getOutputStream());
         ObjectInputStream ois = new ObjectInputStream(client.getInputStream())) {

        System.out.println("Sending request");
        String selectedTable = databaseTableComboBox.getSelectionModel().getSelectedItem();
        oos.writeUTF(selectedTable);
        oos.flush();

        table.getColumns().clear();
        table.getItems().clear();

        ArrayList data = null;
        Builder builder = null;
        switch (selectedTable){
            case "blog_user": builder = new UserBuilder();data = (ArrayList<User>)ois.readObject();break;
        }

        assert builder != null;
        builder.setColumns(table);
        table.getItems().addAll(data);
        table.refresh();
    } catch (IOException | ClassNotFoundException e) {
        e.printStackTrace();
    }
}

有趣的是，它已经工作了一次，但后来我添加了与其他类（例如Admin和AdminBuilder）的User和UserBuilder相同的机制，突然文本不再显示在TableView中

非常感谢所有帮助。
您的用户类需要getter方法。PropertyValueFactory需要访问这些字段

public class User {
    private final int id;
    private final String username;
    private final String pwd;

    public User(int id, String username, String pwd) {
        this.id = id;
        this.username = username;
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return id + " " + username + " " + pwd;
    }

    public int getId() {
        return id;
    }

    public String getUsername() {
        return username;
    }

    public String getPwd() {
        return pwd;
    }

}

谢谢你，成功了。我以前删除过我的getter，因为我认为我不需要它们。
public class User implements Serializable{
    private int id;
    private String username;
    private String pwd;

    public User(int id, String username, String pwd) {
        this.id = id;
        this.username = username;
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return id + " " + username + " " + pwd;
    }
}

public class User {
    private final int id;
    private final String username;
    private final String pwd;

    public User(int id, String username, String pwd) {
        this.id = id;
        this.username = username;
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return id + " " + username + " " + pwd;
    }

    public int getId() {
        return id;
    }

    public String getUsername() {
        return username;
    }

    public String getPwd() {
        return pwd;
    }

}