java - 在JAVA中显示JTable中所有反序列化的对象

Question

我想显示表格中的所有对象。

我有一个名为/menschen 的文件夹，其中包含如下文件:“firstname.lastname.ser”

package adressverwaltung;

import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JLabel;
import javax.swing.JButton;
import javax.swing.JOptionPane;
// FILE
import java.io.*;
import java.util.*;
import java.util.Formatter;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.awt.HeadlessException;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.SpringLayout;

/**
 *
 * @author 
 */
public class Adressverwaltung {

    JFrame mainWindow;
    final File folder = new File("menschen");

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        Adressverwaltung verweiss = new Adressverwaltung();
        verweiss.main();

    }

    public void main() {
        mainWindow = new JFrame();
        mainWindow.setBounds(0, 0, 800, 400);
        mainWindow.setLocationRelativeTo(null);

        mainWindow.setLayout(null);
        mainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        mainWindow.setResizable(false);
        mainWindow.setVisible(true);
        mainWindow.setLayout(new FlowLayout());

        menu();

    }

    public String deserialize(String m, int field) {

        try {

            FileInputStream fin = new FileInputStream("menschen\\" + m);
            ObjectInputStream ois = new ObjectInputStream(fin);
            Person n = (Person) ois.readObject();
            ois.close();

            switch (field) {
                case 1:
                    return n.vorname;
                case 2:
                    return n.nachname;
            }



        } catch (Exception ex) {
            ex.printStackTrace();

        }
        return null;

    }

    public static void table(String[][] alle) {

        String[] columnNames = {
            "Vorname", "Nachname"
        };
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JTable table = new JTable(alle, columnNames);
        f.add(new JScrollPane(table));
        f.pack();
        f.setVisible(true);
    }

    private static void serialize(Person m) {

        try {
            FileOutputStream fileOut =
                    new FileOutputStream("menschen\\" + m.vorname + "." + m.nachname + ".ser");
            ObjectOutputStream out =
                    new ObjectOutputStream(fileOut);
            out.writeObject(m);
            out.close();
            fileOut.close();
        } catch (IOException i) {
        }
    }

    public void menu() {

        JPanel list = new JPanel();

        list.setBorder(BorderFactory.createLineBorder(Color.black));
        list.setPreferredSize(new java.awt.Dimension(400, 360));
        list.setBackground(Color.white);
        mainWindow.add(list);
        // Wir lassen unseren Dialog anzeigen
        mainWindow.setVisible(true);


        int ButtonWidth = 100;
        int ButtonHeight = 30;
        int ButtonTop = 10;

        JButton Button1 = new JButton("List all");
        JButton Button3 = new JButton("Search");

        Button1.setBounds(10, ButtonTop, ButtonWidth, ButtonHeight);
        Button3.setBounds(230, ButtonTop, ButtonWidth, ButtonHeight);

        list.add(Button1);
        list.add(Button3);

        mainWindow.add(list);


        createForm();

        Button1.addActionListener(new ActionListener() {
            public void actionPerformed(final ActionEvent e) {
                list(folder);
            }
        });
    }

    public void list(final File folder) {
        String[][] rowData = new String[3][];

        int r = 0;
        for (final File fileEntry : folder.listFiles()) {
            if (fileEntry.isDirectory()) {
            } else {
                String name = fileEntry.getName();

                rowData[r][0] = deserialize(name, 1);
                rowData[r][1] = deserialize(name, 2);

                r++;
            }
        }

        table(rowData);
    }

    private void createForm() {

        JPanel p = new JPanel();
        p.setLayout(new GridLayout(3, 2));
        JButton b = new JButton("Neue Person!");
        JLabel vornameLabel = new JLabel("Vorname:");
        final JTextField vorname = new JTextField();
        JLabel nachnameLabel = new JLabel("Nachname:");
        final JTextField nachname = new JTextField();

        p.add(vornameLabel);
        p.add(vorname);
        p.add(nachnameLabel);
        p.add(nachname);
        p.add(b);
        p.setBorder(BorderFactory.createLineBorder(Color.black));
        p.setPreferredSize(new java.awt.Dimension(300, 100));
        p.setBackground(Color.white);
        mainWindow.add(p);
        // Wir lassen unseren Dialog anzeigen
        mainWindow.setVisible(true);

        b.addActionListener(new ActionListener() {
            public void actionPerformed(final ActionEvent e) {
                Person m = new Person(vorname.getText(), nachname.getText());
                serialize(m);
                JOptionPane.showMessageDialog(null, vorname.getText() + "." + nachname.getText() + ".ser abgespeichert.", "Tutorial 2", JOptionPane.INFORMATION_MESSAGE);
            }
        });
    }
}

这是我的 Person 类:

package adressverwaltung;

/**
 *
 * @author Mahshid
 */
class Person implements java.io.Serializable {
    // Allgemeine Kontaktinformationen:

    public String vorname;
    public String nachname;
    // Adresse
    public String strasse;
    public int hausnummer;
    public int postleitzahl;
    public String ort;
    public String land;
    // Telefon
    public int mobil;
    public int festnetz;
    // Email & Kommentar
    public String mail;
    public String kommentar;

    Person(String vorname, String nachname) {
        this.vorname = vorname;
        this.nachname = nachname;
    }
}

我认为 list() 函数有问题。这是我的第一个 Java 代码，所以如果您看到任何大错误，请不要感到惊讶:)

Answer 1

通过创建这样的二维数组:

String[][] rowData = new String[3][];

您正在创建一个数组，其中所有“列”数据均未初始化。您可以通过执行以下操作来亲自检查:

for (String[] s: rowData) {
   System.out.println(s); 
}

因此，尝试将任何外部数组元素分配给单个 String 是不可能的:

rowData[r][0] = deserialize(name, 1);