Mysql Problems

// Main.java

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author Rajan Alex
 */
import TableModel.DisplayResult;

public class Main {



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


// DisplayResult.java

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package TableModel;

import java.awt.BorderLayout;
import java.awt.event.*;
import java.sql.SQLException;
import javax.swing.*;
import javax.swing.table.*;

/**
 *
 * @author Rajan Alex
 */
public class DisplayResult extends JFrame {

 

    String url = "jdbc:mysql://localhost:3306/university";

    String username = "root";
    String password = "194157";
    static final String defaultQuery = "select * from instructor";
    private ResultSetTableModel tableModel;
    private JTextArea queryArea;

    public DisplayResult() {
        super("Displaying Query Result");
        try {
            tableModel = new ResultSetTableModel(url, username, password, defaultQuery);
            queryArea = new JTextArea("Enter your query here", 3, 100);
            queryArea.setWrapStyleWord(true);
            queryArea.setLineWrap(true);
            JScrollPane scrollPane =
                    new JScrollPane(queryArea,
                    ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
                    ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
            JButton submitButton = new JButton("Submit Query");
            Box northBox = Box.createHorizontalBox();
            northBox.add(scrollPane);
            northBox.add(submitButton);
            JTable resultTable = new JTable(tableModel);
            add(northBox, BorderLayout.NORTH);
            add(new JScrollPane(resultTable), BorderLayout.CENTER);
            submitButton.addActionListener(
                    new ActionListener() {

                        public void actionPerformed(ActionEvent e) {
                            try {
                                tableModel.setQuery(queryArea.getText());
                            } catch (SQLException sqle) {
                                JOptionPane.showMessageDialog(null,
                                        sqle.getMessage(), "Database error",
                                        JOptionPane.ERROR_MESSAGE);
                                try {
                                    tableModel.setQuery(defaultQuery);
                                    queryArea.setText(defaultQuery);
                                } catch (SQLException sqle1) {
                                    JOptionPane.showMessageDialog(null,
                                            sqle1.getMessage(), "Database error",
                                            JOptionPane.ERROR_MESSAGE);
                                    tableModel.disconnectFromDatabase();
                                    System.exit(1);
                                }
                            }
                        } //end method
                    });
            final TableRowSorter<TableModel> sorter =
                    new TableRowSorter<TableModel>(tableModel);
            resultTable.setRowSorter(sorter);
            setSize(500, 250);
            setVisible(true);
            addWindowListener(new WindowAdapter() {

                public void windowClosed(WindowEvent we) {
                    tableModel.disconnectFromDatabase();
                    System.exit(0);
                }
            });
        } catch (SQLException sqle) {
            JOptionPane.showMessageDialog(null,
                    sqle.getMessage(), "Database error",
                    JOptionPane.ERROR_MESSAGE);
            tableModel.disconnectFromDatabase();
            System.exit(1);
        }
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);

    }
}


// ResultSetTableModel.java

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package TableModel;

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

/**
 *
 * @author Rajan Alex
 */
public class ResultSetTableModel extends AbstractTableModel {

    // experts exchange

    private Connection connection;
    private Statement statement;
    private ResultSet resultSet;
    private ResultSetMetaData metaData;
    private boolean connectedToDatabase;
    private int numberOfRows;

    public ResultSetTableModel(String url, String userName, String password,
            String query) throws SQLException {
        connection = DriverManager.getConnection(url, userName, password);
        statement = connection.createStatement(); // i am not sure of parameters
        connectedToDatabase = true;
        setQuery(query);

    }

    public Class getColumnClass(int c) throws IllegalStateException {
        if (!connectedToDatabase) {
            throw new IllegalStateException("Not connected to database");
        }
        try {
            String className = metaData.getColumnClassName(+1);
            return Class.forName(className);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return Object.class; // to ingore while compiling
    }

    public int getColumnCount() throws IllegalStateException {
        if (!connectedToDatabase) {
            throw new IllegalStateException("Not connected to database");
        }
        try {
            return metaData.getColumnCount();
        } catch (SQLException sqle) {
            sqle.printStackTrace();
        }
        return 0;  // if problems occur above
    }

    public String getColumnName(int c) throws IllegalStateException {
        if (!connectedToDatabase) {
            throw new IllegalStateException("Not connected to database");
        }
        try {
            return metaData.getColumnName(c + 1);
        } catch (SQLException sqle) {
            sqle.printStackTrace();
        }
        return ""; // if problem occur above
    }

    public int getRowCount() throws IllegalStateException {
        if (!connectedToDatabase) {
            throw new IllegalStateException("Not connected to database");
        }
        return numberOfRows;
    }

    public Object getValueAt(int r, int c) throws IllegalStateException {
        if (!connectedToDatabase) {
            throw new IllegalStateException("Not connected to database");
        }
        try {
            resultSet.absolute(r + 1);
            return resultSet.getObject(c + 1);
        } catch (SQLException sqle) {
            sqle.printStackTrace();
        }
        return ""; // if problem occur above
    }

    public void setQuery(String st) throws SQLException, IllegalStateException {
        if (!connectedToDatabase) {
            throw new IllegalStateException("Not connected to database");
        }
        resultSet = statement.executeQuery(st);
        metaData = resultSet.getMetaData();
        resultSet.last();
        numberOfRows = resultSet.getRow();
        fireTableStructureChanged();
    }

    public void disconnectFromDatabase() {
        if (connectedToDatabase) {
            try {
                resultSet.close();
                statement.close();
                connection.close();
            } catch (SQLException sqle) {
                sqle.printStackTrace();
            } finally {
                connectedToDatabase = false;
            }
        }
    }
}

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