مشكلة فى عرض بيانات من قاعدة البيانات إلى Jtable

هنا أقوم بكتابة code يعرض بيانات من قاعدة بينات إلى Jtable

بيظهر nullPointerexception مش عارف ايه سببه فى السطر هذا

   metaData = resultSet.getMetaData();

أنا بخمن عشان ان ال resultset ليس لها Intialization لكن فوق السطر هذا يوجد دالة setQuery() و بها intialization لل resultset إذن ما العيب ؟؟

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الكود

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import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyVetoException;
import java.sql.SQLException;
import javax.swing.JButton;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.TableModel;
import javax.swing.table.TableRowSorter;

public class TestJtable extends JFrame {

    private JPanel mainPanel, buttonPanel;
    private JButton[] buttons;
    private final String[] BUTTONNAMES = {"showButton", "insertButton", "searchButton", "updateButton", "deletebutton"};
    private JInternalFrame internalFrame;
    private JDesktopPane desktopPane;
    private JTable table;
    private ResultTableModel tableModel;
    private JScrollPane scrollPane;
    private static final String showData = "SELECT * FROM Employee";
    private MyActionListener myActionListener;

    public TestJtable() throws ClassNotFoundException, SQLException {
        intializingPanels();
        intializingbuttons();
        tableModel = new ResultTableModel();
        table = new JTable(tableModel);
        tableModelOperations();
        scrollPane = new JScrollPane(table, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS,
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        getContentPane().add(mainPanel);
    }

    public static void main(String[] args) throws SQLException, ClassNotFoundException {
        TestJtable testJtable = new TestJtable();
        testJtable.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        testJtable.setSize(new Dimension(600, 300));
        testJtable.setLocationRelativeTo(null);
        testJtable.setVisible(true);
    }

    private void intializingPanels() {
        mainPanel = new JPanel(new BorderLayout());
        buttonPanel = new JPanel(new FlowLayout());

    }

    private void intializingbuttons() {
        myActionListener = new MyActionListener();
        buttons = new JButton[BUTTONNAMES.length];
        for (int i = 0; i < BUTTONNAMES.length; i++) {
            buttons = new JButton(BUTTONNAMES);
            buttons.addActionListener(myActionListener);
            buttonPanel.add(buttons);
            mainPanel.add(buttonPanel, BorderLayout.NORTH);
        }
    }

    private void intializingInternalDeskTop() {

        JPanel panel = new JPanel(new BorderLayout());
        panel.add(scrollPane, BorderLayout.CENTER);
        /////////////////////////////////////////////////////////////
        internalFrame = new JInternalFrame(null, true, true, true);
        internalFrame.setSize(500, 500);
        internalFrame.add(panel);
        try {
            internalFrame.setMaximum(true);
        } catch (PropertyVetoException ex) {
            ex.printStackTrace();
        }
        //////////////////////////////////////////////////////////////
        desktopPane = new JDesktopPane();
        desktopPane.setOpaque(false);
        desktopPane.setEnabled(true);
        desktopPane.add(internalFrame);
        internalFrame.setVisible(true);
        //////////////////////////////////////////////////////////////
        mainPanel.add(desktopPane, BorderLayout.CENTER);
    }

    private void tableModelOperations() throws SQLException {
        tableModel.setQuery(showData);
        tableModel.disconnectedDatabase();
        TableRowSorter<TableModel> sorter = new TableRowSorter<TableModel>(tableModel);
        table.setRowSorter(sorter);
    }

    private class MyActionListener implements ActionListener {

        public void actionPerformed(ActionEvent e) {
            if (e.getSource() == buttons[0]) {
                intializingInternalDeskTop();

            }
        }
    }
}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import javax.swing.table.AbstractTableModel;

public class ResultTableModel extends AbstractTableModel {

    private static final String DRIVER = "sun.jdbc.odbc.JdbcOdbcDriver";
    private static final String DRIVER_URL = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};" +
            "Dbq=D:\\my _works\\my_works_2010\\JDBC-work\\employeedb\\Database2.mdb";
    private Connection connection;
    private Statement statement;
    private ResultSet resultSet;
    private ResultSetMetaData metaData;
    private String query;
    private int numOfRow;
    private boolean connect = false;

    public ResultTableModel() throws ClassNotFoundException, SQLException {
        Class.forName(DRIVER);
        connection = DriverManager.getConnection(DRIVER_URL);
        statement = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
                ResultSet.CONCUR_READ_ONLY);
        connect = true;
        if (query != null) {
            setQuery(query);
        }
        metaData = resultSet.getMetaData();
    }

    @Override
    public Class getColumnClass(int columnIndex) {
        try {
            String className = metaData.getColumnClassName(columnIndex + 1);
            return Class.forName(className);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return Object.class;
    }

    @Override
    public int getColumnCount() {
        try {
            return metaData.getColumnCount();
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
        return 0;
    }

    @Override
    public String getColumnName(int column) {
        try {
            return metaData.getColumnName(column + 1);
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
        return "";
    }

    public int getRowCount() {
        return numOfRow;
    }

    public Object getValueAt(int rowIndex, int columnIndex) {
        try {
            resultSet.absolute(rowIndex + 1);
            return resultSet.getObject(columnIndex + 1);
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
        return "";
    }

    public void setQuery(String query) throws SQLException {
        resultSet = statement.executeQuery(query);
        metaData = resultSet.getMetaData();
        resultSet.last();
        numOfRow = resultSet.getRow();
        fireTableStructureChanged();
    }

    public void disconnectedDatabase() throws SQLException {
        if (connect) {
            resultSet.close();
            statement.close();
            connection.close();
        }
    }
}

و هل هذه الطريقة لعرض بيانا فى JTabel سليمة .؟؟؟ لو أحد عنده طريقة أفضل يعرضها

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