java - 在java中创建表

Question

我正在尽力在 java 应用程序中的列表旁边创建只读表(空白，但准备获取列内容和行名称)，但我仍然无法弄清楚这些表有什么问题

<小时/>

我得到了异常(exception)

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 0 at examples.TableData.getColumnCount(TableData.java:25) at javax.swing.JTable.createDefaultColumnsFromModel(JTable.java:1285) at javax.swing.JTable.tableChanged(JTable.java:4386) at javax.swing.JTable.setModel(JTable.java:3688) at javax.swing.JTable.(JTable.java:632) at javax.swing.JTable.(JTable.java:573) at examples.Main$2.run(Main.java:77) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756) at java.awt.EventQueue.access$500(EventQueue.java:97) at java.awt.EventQueue$3.run(EventQueue.java:709) at java.awt.EventQueue$3.run(EventQueue.java:703) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75) at java.awt.EventQueue.dispatchEvent(EventQueue.java:726) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) BUILD SUCCESSFUL (total time: 5 seconds)

---

这是主文件:

/* Програма с графичен интерфейс (swing/awt), която
 * извежда продуктовите категории от базата данни на "northwind"
 * и изкарва информация за продуктите в нея
*/

package examples;

/* Компоненти на swing */
import javax.swing.SwingUtilities;
import javax.swing.JList;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.JTable;
import javax.swing.table.TableColumn;
import javax.swing.table.TableColumnModel;
/* Компоненти на awt */
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Container;
import java.awt.BorderLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
/* Компоненти на SQL ?? */

public class Main
{
    public static void main(String[] args)
    {
        /* ЗАГЛАВИЕ на прозорец, добавяне на    КОНТЕЙНЪР в прозореца */
        JFrame frame = new JFrame("Product Exmplorer");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Container contentPane = frame.getContentPane();

        /* Използване на JList                  ЛИСТ */
        String labels[] = { "Test1", "Test2" };
        JList jlist = new JList(labels);

        /* Слагане на                           ПЛЪЗГАЧИ в контейнъра */
        JScrollPane scrollPane1 = new JScrollPane(jlist);
        contentPane.add(scrollPane1, BorderLayout.EAST);

        /**********************************************************************/
        /* Дефиниране на                        ЛИСЪНЪР за клик */
        MouseListener mouseListener = new MouseAdapter()
        {
            public void mouseClicked(MouseEvent mouseEvent)
            {
                JList theList = (JList) mouseEvent.getSource();
                if (mouseEvent.getClickCount() == 2)
                {
                    int index = theList.locationToIndex(mouseEvent.getPoint());
                    if (index >= 0)
                    {
                        Object o = theList.getModel().getElementAt(index);
                        System.out.println("Double-clicked on: " + o.toString());
                    }
                }
            }
        };
        jlist.addMouseListener(mouseListener);

        /**********************************************************************/

        Runnable runner = new Runnable() // анонимен клас
        {
            @Override
            public void run()
            {
                JFrame frame = new JFrame("Button model");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                // създаване на таблицата
                TableData td = new TableData();
                JTable table = new JTable(td);
                table.setAutoResizeMode(JTable.AUTO_RESIZE_NEXT_COLUMN);

                JScrollPane scrollPane = new JScrollPane(table);
                frame.add(scrollPane , BorderLayout.CENTER);

                frame.pack();
                frame.setVisible(true);
            }
        };

        SwingUtilities.invokeLater(runner);
    }
}

<小时/>

这是所需的源包:

package examples;

import java.util.Calendar;
import java.util.GregorianCalendar;
import javax.swing.table.AbstractTableModel;

public class TableData extends AbstractTableModel
{
    //Row & Column Data
    private Object[][] values =
    {
    };
    private final String[] columnHeaders = {
      "Име", "Фамилия", "Роден(а) на", "Сума", "Пол"  
    };

    @Override
    public int getRowCount()
    {
        return values.length;
    }
    @Override
    public int getColumnCount()
    {
        return values[0].length;
    }
    @Override
    public Object getValueAt(int rowIndex, int columnIndex)
    {
        return values[rowIndex][columnIndex];
    }
    //--------------------------------------------------------------------------
}

<小时/>

我即将做最可怕的噩梦

Answer 1

在

TableData extends AbstractTableModel
{
    //Row & Column Data
    private Object[][] values =

在哪里初始化“值”？它看起来是空的。

在

public int getColumnCount()
{
    return values[0].length;
}

您正在尝试访问值[0]，而不检查是否存在“值[0]”。