Hi
I am using netbeans and mysql. I am trying to run the an inventory system. I have linked the program with mysql. The program is running but when in log in page I input username and password which is preinstalled in mysql and then press submit, its not going to next page but giving this error on netbeans:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at frame.Admin.jButton8ActionPerformed(Admin.java:360)
        at frame.Admin.access$300(Admin.java:14)
        at frame.Admin$4.actionPerformed(Admin.java:200)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.Component.processMouseEvent(Component.java:6263)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
        at java.awt.Component.processEvent(Component.java:6028)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2478)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Looking at the stack trace, because it is very difficult for you to just read the error messages and you need someone else to do this for you,
I saw this:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at frame.Admin.jButton8ActionPerformed(Admin.java:360)

You have a NullPointerException at the Admin.java file at line 360

You are using something which is null, something which is not initialized. Try and see what is going on around that line and then if you can't fix it, post the code around that line, indicating which line it is

/*
 * Admin.java
 *
 * Created on July 16, 2009, 2:54 AM
 */

package frame;
import java.sql.*;
import javax.swing.*;
/**
 *
 * @author  ziaul
 */
public class Admin extends javax.swing.JFrame {
     String driver="com.mysql.jdbc.Driver";
    String url="jdbc:mysql://localhost:3306/emarket1";
    Connection con=null;
    PreparedStatement st=null;
    static int back=0;
    static int front=0;
    /** Creates new form Admin */
    public Admin(int f,int b) {
        
         try{
       initComponents();
      if(b<0)
            ;
      else
        back=b;
       
      if(f<0)
            ;
      else
        front=f;
       
      
       
       Class.forName(driver);
       con=DriverManager.getConnection(url,"root","389");
       
    
    }
    catch(ClassNotFoundException e){}
   catch(SQLException e){}
    }
    
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel4 = new javax.swing.JPanel();
        jPanel5 = new javax.swing.JPanel();
        jPanel6 = new javax.swing.JPanel();
        jLabel2 = new javax.swing.JLabel();
        jLabel1 = new javax.swing.JLabel();
        jPanel7 = new javax.swing.JPanel();
        jButton5 = new javax.swing.JButton();
        jButton3 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();
        jPanel8 = new javax.swing.JPanel();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        jTextField2 = new javax.swing.JTextField();
        jCheckBox1 = new javax.swing.JCheckBox();
        jButton8 = new javax.swing.JButton();
        jPanel9 = new javax.swing.JPanel();
        jLabel7 = new javax.swing.JLabel();
        jPasswordField = new javax.swing.JPasswordField();
        jSeparator1 = new javax.swing.JSeparator();
        jSeparator2 = new javax.swing.JSeparator();
        jLabel5 = new javax.swing.JLabel();
        jLabel6 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Administrator");

        jPanel4.setBackground(new java.awt.Color(2, 48, 48));
        jPanel4.setForeground(new java.awt.Color(0, 0, 255));

        jPanel5.setBackground(new java.awt.Color(83, 83, 3));

        jPanel6.setBackground(java.awt.Color.black);

        jLabel2.setFont(new java.awt.Font("Lucida Calligraphy", 1, 48));
        jLabel2.setForeground(java.awt.Color.white);
        jLabel2.setText("Inventory Control System");

        jLabel1.setFont(new java.awt.Font("Bradley Hand ITC", 1, 18));
        jLabel1.setForeground(new java.awt.Color(204, 0, 0));
        jLabel1.setText("Designed by Group  Cryptic - STM LONDON 2010");

        javax.swing.GroupLayout jPanel6Layout = new javax.swing.GroupLayout(jPanel6);
        jPanel6.setLayout(jPanel6Layout);
        jPanel6Layout.setHorizontalGroup(
            jPanel6Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel6Layout.createSequentialGroup()
                .addContainerGap(316, Short.MAX_VALUE)
                .addComponent(jLabel1)
                .addGap(186, 186, 186))
            .addGroup(jPanel6Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 793, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(127, Short.MAX_VALUE))
        );
        jPanel6Layout.setVerticalGroup(
            jPanel6Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel6Layout.createSequentialGroup()
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jLabel2)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jLabel1))
        );

        jPanel7.setBackground(new java.awt.Color(87, 75, 8));
        jPanel7.setLayout(new java.awt.GridLayout(1, 0));

        jButton5.setBackground(new java.awt.Color(153, 153, 0));
        jButton5.setIcon(new javax.swing.ImageIcon(getClass().getResource("/frame/backover.jpg"))); // NOI18N
        jButton5.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton5ActionPerformed(evt);
            }
        });

        jButton3.setBackground(new java.awt.Color(153, 153, 0));
        jButton3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/frame/home.gif"))); // NOI18N
        jButton3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton3ActionPerformed(evt);
            }
        });

        jButton2.setIcon(new javax.swing.ImageIcon(getClass().getResource("/frame/nextdown.jpg"))); // NOI18N

        javax.swing.GroupLayout jPanel5Layout = new javax.swing.GroupLayout(jPanel5);
        jPanel5.setLayout(jPanel5Layout);
        jPanel5Layout.setHorizontalGroup(
            jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel5Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel5Layout.createSequentialGroup()
                        .addComponent(jPanel6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addContainerGap())
                    .addGroup(jPanel5Layout.createSequentialGroup()
                        .addComponent(jPanel7, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addComponent(jButton5, javax.swing.GroupLayout.PREFERRED_SIZE, 36, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(26, 26, 26)
                        .addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 36, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(33, 33, 33)
                        .addComponent(jButton3, javax.swing.GroupLayout.PREFERRED_SIZE, 36, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(967, 967, 967))))
        );
        jPanel5Layout.setVerticalGroup(
            jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel5Layout.createSequentialGroup()
                .addComponent(jPanel6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addGroup(jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel5Layout.createSequentialGroup()
                        .addGap(24, 24, 24)
                        .addComponent(jPanel7, javax.swing.GroupLayout.DEFAULT_SIZE, 20, Short.MAX_VALUE))
                    .addGroup(jPanel5Layout.createSequentialGroup()
                        .addGap(6, 6, 6)
                        .addGroup(jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                            .addComponent(jButton3, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.PREFERRED_SIZE, 30, Short.MAX_VALUE)
                            .addComponent(jButton5, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(jButton2, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))))
                .addContainerGap())
        );

        jPanel8.setBorder(javax.swing.BorderFactory.createTitledBorder(null, "For administrator", javax.swing.border.TitledBorder.DEFAULT_JUSTIFICATION, javax.swing.border.TitledBorder.DEFAULT_POSITION, new java.awt.Font("Times New Roman", 1, 12), new java.awt.Color(13, 13, 237))); // NOI18N

        jLabel3.setFont(new java.awt.Font("Tahoma", 1, 18));
        jLabel3.setForeground(new java.awt.Color(0, 0, 255));
        jLabel3.setText("USER NAME");

        jLabel4.setFont(new java.awt.Font("Tahoma", 1, 18));
        jLabel4.setForeground(java.awt.Color.blue);
        jLabel4.setText("PASSWORD");

        jTextField2.setFont(new java.awt.Font("Tahoma", 0, 14)); // NOI18N
        jTextField2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField2ActionPerformed(evt);
            }
        });

        jCheckBox1.setFont(new java.awt.Font("Tahoma", 1, 14));
        jCheckBox1.setText("REMEMBER ME NEXT TIME");

        jButton8.setText("LOGIN");
        jButton8.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton8ActionPerformed(evt);
            }
        });

        jPanel9.setBackground(new java.awt.Color(209, 179, 8));

        jLabel7.setFont(new java.awt.Font("Tahoma", 1, 18));
        jLabel7.setForeground(new java.awt.Color(0, 0, 255));
        jLabel7.setText("Login");

        javax.swing.GroupLayout jPanel9Layout = new javax.swing.GroupLayout(jPanel9);
        jPanel9.setLayout(jPanel9Layout);
        jPanel9Layout.setHorizontalGroup(
            jPanel9Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel9Layout.createSequentialGroup()
                .addContainerGap(302, Short.MAX_VALUE)
                .addComponent(jLabel7, javax.swing.GroupLayout.PREFERRED_SIZE, 94, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(234, 234, 234))
        );
        jPanel9Layout.setVerticalGroup(
            jPanel9Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jLabel7, javax.swing.GroupLayout.DEFAULT_SIZE, 33, Short.MAX_VALUE)
        );

        jPasswordField.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jPasswordFieldActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel8Layout = new javax.swing.GroupLayout(jPanel8);
        jPanel8.setLayout(jPanel8Layout);
        jPanel8Layout.setHorizontalGroup(
            jPanel8Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel8Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel9, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel8Layout.createSequentialGroup()
                .addGroup(jPanel8Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addGroup(jPanel8Layout.createSequentialGroup()
                        .addGap(85, 85, 85)
                        .addGroup(jPanel8Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(jPanel8Layout.createSequentialGroup()
                                .addComponent(jLabel4)
                                .addGap(18, 18, 18)
                                .addComponent(jPasswordField, javax.swing.GroupLayout.DEFAULT_SIZE, 400, Short.MAX_VALUE))
                            .addGroup(jPanel8Layout.createSequentialGroup()
                                .addComponent(jLabel3)
                                .addGap(18, 18, 18)
                                .addComponent(jTextField2, javax.swing.GroupLayout.DEFAULT_SIZE, 400, Short.MAX_VALUE))))
                    .addGroup(jPanel8Layout.createSequentialGroup()
                        .addContainerGap()
                        .addComponent(jCheckBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 263, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jButton8, javax.swing.GroupLayout.PREFERRED_SIZE, 79, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addGap(41, 41, 41))
        );
        jPanel8Layout.setVerticalGroup(
            jPanel8Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel8Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel9, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(4, 4, 4)
                .addGroup(jPanel8Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel3)
                    .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(12, 12, 12)
                .addGroup(jPanel8Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jLabel4)
                    .addComponent(jPasswordField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGroup(jPanel8Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel8Layout.createSequentialGroup()
                        .addGap(32, 32, 32)
                        .addComponent(jButton8))
                    .addGroup(jPanel8Layout.createSequentialGroup()
                        .addGap(18, 18, 18)
                        .addComponent(jCheckBox1)))
                .addGap(78, 78, 78))
        );

        jLabel5.setFont(new java.awt.Font("Times New Roman", 1, 18));
        jLabel5.setForeground(new java.awt.Color(255, 255, 255));
        jLabel5.setText("*To update, add, delete or modify any product you must need to login");

        jLabel6.setFont(new java.awt.Font("Times New Roman", 1, 18));
        jLabel6.setForeground(new java.awt.Color(255, 255, 255));
        jLabel6.setText("* To login please input user name & password. ");

        javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4);
        jPanel4.setLayout(jPanel4Layout);
        jPanel4Layout.setHorizontalGroup(
            jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel4Layout.createSequentialGroup()
                .addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel4Layout.createSequentialGroup()
                        .addGap(202, 202, 202)
                        .addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addComponent(jSeparator1, javax.swing.GroupLayout.PREFERRED_SIZE, 539, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jSeparator2, javax.swing.GroupLayout.PREFERRED_SIZE, 539, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(jPanel4Layout.createSequentialGroup()
                        .addGap(108, 108, 108)
                        .addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel6)
                            .addComponent(jLabel5)
                            .addComponent(jPanel8, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(jPanel4Layout.createSequentialGroup()
                        .addContainerGap()
                        .addComponent(jPanel5, javax.swing.GroupLayout.PREFERRED_SIZE, 934, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(77, Short.MAX_VALUE))
        );
        jPanel4Layout.setVerticalGroup(
            jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel4Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jPanel5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(50, 50, 50)
                .addComponent(jLabel5)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jLabel6)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 78, Short.MAX_VALUE)
                .addComponent(jPanel8, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(jSeparator1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(29, 29, 29)
                .addComponent(jSeparator2, javax.swing.GroupLayout.PREFERRED_SIZE, 10, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(97, 97, 97))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(76, 76, 76)
                .addComponent(jPanel4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        

    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         
       front=1; 
        new NewJFrame(-1,2).setVisible(true);
        this.setVisible(false);// TODO add your handling code here:
    }                                        

    private void jButton8ActionPerformed(java.awt.event.ActionEvent evt) {                                         
      try{
            String username= jTextField2.getText();
            String password=new String(jPasswordField.getPassword());
            //password=password.substring(0, password.lastIndexOf('1'));
            
            st=con.prepareStatement("select * from admin where name=? and password=?");
            st.setString(1, username);
            st.setString(2, password);
            st.execute();
            ResultSet r=st.getResultSet();
            r.last();
            int n=0;n=r.getRow();
            
            if(n!=0) {
                
                JOptionPane.showMessageDialog(null,"succesfully login");
                String s=r.getObject(1).toString();
                this.setVisible(false);
                front=9;
                controlling f=new controlling(-1,2);
               
                f.setVisible(true);
            }
            
            else {
                JOptionPane.showMessageDialog(null,"login failed!");
                jTextField2.setText("");
                jPasswordField.setText("");
                
            }
            
            
            
        } catch(SQLException e){}
        
        // TODO add your handling code here:
    }                                        

    private void jButton5ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
    }                                        

    private void jTextField2ActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
    }                                           

    private void jPasswordFieldActionPerformed(java.awt.event.ActionEvent evt) {                                               
        // TODO add your handling code here:
    }                                              
    
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
               // new Admin().setVisible(true);
            }
        });
    }
    
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JButton jButton5;
    private javax.swing.JButton jButton8;
    private javax.swing.JCheckBox jCheckBox1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JLabel jLabel6;
    private javax.swing.JLabel jLabel7;
    private javax.swing.JPanel jPanel4;
    private javax.swing.JPanel jPanel5;
    private javax.swing.JPanel jPanel6;
    private javax.swing.JPanel jPanel7;
    private javax.swing.JPanel jPanel8;
    private javax.swing.JPanel jPanel9;
    private javax.swing.JPasswordField jPasswordField;
    private javax.swing.JSeparator jSeparator1;
    private javax.swing.JSeparator jSeparator2;
    private javax.swing.JTextField jTextField2;
    // End of variables declaration                   
    
}

If anyone can find out what the problem is, it will be really great

I'm guessing your connection "con" is null. It probably failed to get the connection and you would never know it because you've discarded the exception information

catch(ClassNotFoundException e){}
catch(SQLException e){}

That's why empty catch blocks are a bad idea.

thanks who has given the comments but the problem has not been sorted yet.
Can anyone help me how to sort out this problem.

Edited 6 Years Ago by ziaul1234: n/a

Put e.printStackTrace() into those empty catch blocks and find out if your connection attempt is failing.

Hi tried to edit and its not working. it is now showing

java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:946)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2941)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:868)
        at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:3340)
        at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1238)
        at com.mysql.jdbc.Connection.createNewIO(Connection.java:2743)
        at com.mysql.jdbc.Connection.<init>(Connection.java:1553)
        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266)
        at java.sql.DriverManager.getConnection(DriverManager.java:582)
        at java.sql.DriverManager.getConnection(DriverManager.java:185)
        at frame.Admin.<init>(Admin.java:39)
        at frame.NewJFrame.jButton11ActionPerformed(NewJFrame.java:412)
        at frame.NewJFrame.access$200(NewJFrame.java:14)
        at frame.NewJFrame$3.actionPerformed(NewJFrame.java:148)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.Component.processMouseEvent(Component.java:6263)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
        at java.awt.Component.processEvent(Component.java:6028)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2478)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

So there is the problem. What did you try to fix it?

I would like to agree with Ezzaral and add some more comments.
In previous post you have been told the location of the error and asked to post relevant code indicating where the line was.
Then you posted your entire code, leaving us to search where in the world was that line with the error, even though you've been told which line was that and to post only that.

Also please next time to read the errors that you get. They are followed by very explanatory descriptions:

java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:946)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2941)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:868)
at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:3340)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1238)
at com.mysql.jdbc.Connection.createNewIO(Connection.java:2743)
at com.mysql.jdbc.Connection.<init>(Connection.java:1553)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at frame.Admin.<init>(Admin.java:39)

Are you sure that you are using the right username, password? Try to connect to the mysql command prompt using that username and password that you have in your code:

con=DriverManager.getConnection(url,"root","389");

Is it working? What combination did you use to login? Or you have set it so it won't need a password,
If you do not want to share that information it is understandable.
Your next move would be to check the API for the class: java.sql.DriverManager and check the description of the getConnection methods.

This article has been dead for over six months. Start a new discussion instead.