创建最初为空但允许用户动态添加行的Java表模型 [英] Creating a Java Table Model which is initially empty but allows dynamic addition of rows by user

问题描述

我正在创建一个主要功能包含在JTable中的应用程序。我需要使用addRow方法创建一个附带的表模型，用户在窗口中输入详细信息，并在单击JButton时将数据引入一个数组，该数组将传递给addRow（）方法以添加到表中。然而，似乎不可能创建一个空表，在我为10行的行创建二维数组的情况下，在渲染表时，编译器在'JTable.prepareRenderer'方法中标记NullPointerException。

I am making an application whose main function is encompassed in a JTable. I need to make an accompanying table model with an addRow method, the user enters details in the window and upon clicking a JButton the data is brought in to an array which is passed to the addRow() method for addition to the table. It appears to be impossible to make an empty table however, in the case that I make a two dimensional array for rows with 10 rows, when rendering the table the compiler flags up a NullPointerException within the 'JTable.prepareRenderer' method.

我希望我需要做的事情已经明确了！

I hope what I need to do has been made clear!

推荐答案

这里是您的示例代码。您可以根据自己的要求轻松修改它。

Here is sample code for you. You can easily modify it according to your requirements.

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;

public class FrmTable extends JFrame{
    private JTable table;
    private JButton btnAdd;
    private DefaultTableModel tableModel;
    private JTextField txtField1;
    private JTextField txtField2;

    private FrmTable() {
        createGUI();
    }

    private void createGUI() {
        setLayout(new BorderLayout());
        JScrollPane pane = new JScrollPane();
        table = new JTable();
        pane.setViewportView(table);
        JPanel eastPanel = new JPanel();
        btnAdd = new JButton("Add");
        eastPanel.add(btnAdd);
        JPanel northPanel = new JPanel();
        txtField1 = new JTextField();
        txtField2 = new JTextField();
        JLabel lblField1 = new JLabel("Column1   ");
        JLabel lblField2 = new JLabel("Column2   ");
        northPanel.add(lblField1);
        northPanel.add(txtField1);
        northPanel.add(lblField2);
        northPanel.add(txtField2);
        txtField1.setPreferredSize(lblField1.getPreferredSize());
        txtField2.setPreferredSize(lblField2.getPreferredSize());

        add(northPanel, BorderLayout.NORTH);
        add(eastPanel, BorderLayout.EAST);
        add(pane,BorderLayout.CENTER);
        tableModel = new DefaultTableModel(new Object[]{"column1","column2"},0);
        table.setModel(tableModel);
        btnAdd.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                int count = tableModel.getRowCount()+1;
                tableModel.addRow(new Object[]{txtField1.getText(),txtField1.getText()});
            }
        });
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                FrmTable frm = new FrmTable();
                frm.setLocationByPlatform(true);
                frm.pack();
                frm.setDefaultCloseOperation(EXIT_ON_CLOSE);
                frm.setVisible(true);

            }

        });
    }
} 

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