Java将0打印到JTable中的空单元格

import javax.swing.*;
import javax.swing.table.DefaultTableModel;

public class Main {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        JTable table = new JTable(new CustomTableModel());
        frame.add(new JScrollPane(table));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}

class CustomTableModel extends DefaultTableModel {
    @Override
    public Object getValueAt(int row, int column) {
        Object value = super.getValueAt(row, column);
        if (value == null) {
            return 0;
        }
        return value;
    }
}