Netbeans - mi codigo tiene un error y no se por que no quiere almacenar

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package carreteras;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.logging.Level;

import java.util.logging.Logger;

import javax.swing.JOptionPane;

import javax.swing.table.DefaultTableModel;

/**

 *

 * @author rhopm

 */

public class NewJFrame extends javax.swing.JFrame {

    /**

     * Creates new form NewJFrame

     */

    public NewJFrame() {

        initComponents();

        mostrardatos("");

    }

void mostrardatos(String valor){

        conectar cc=new conectar();

        Connection cn=cc.carreteras();

        DefaultTableModel modelo=new DefaultTableModel();

        modelo.addColumn("Estado");

        modelo.addColumn("Municipio");

        modelo.addColumn("Ciudad");

        modelo.addColumn("Carretera");

        jTable1.setModel(modelo);

        String sql="";

        if (valor.equals(""))

        {

            sql="SELECT * FROM idcarreteras";

        }

        else{

            sql="SELECT * FROM idcarreteras WHERE (Estado='"+valor+"'  OR Mucipio='"+valor+"' OR Ciudad='"+valor+"'OR Carretera='"+valor+"')";

        }

        String []datos=new String [2];

        try{

            Statement st=cn.createStatement();

            ResultSet rs=st.executeQuery(sql);

            while(rs.next()){

            datos[0]=rs.getString(1);

            datos[1]=rs.getString(2);

            modelo.addRow(datos);

            }

            jTable1.setModel(modelo);

        }catch(SQLException ex){

            Logger.getLogger(datos.class.getName()).log(Level.SEVERE,null,ex);

        }

    }

    /**

     * 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.

     */

    @SuppressWarnings("unchecked")

    // <editor-fold defaultstate="collapsed" desc="Generated Code">

    private void initComponents() {

        jPopupMenu1 = new javax.swing.JPopupMenu();

        jMenuItem1 = new javax.swing.JMenuItem();

        jMenuItem2 = new javax.swing.JMenuItem();

        jLabel1 = new javax.swing.JLabel();

        jLabel2 = new javax.swing.JLabel();

        jLabel3 = new javax.swing.JLabel();

        jLabel4 = new javax.swing.JLabel();

        jLabel5 = new javax.swing.JLabel();

        jTextField1 = new javax.swing.JTextField();

        jTextField2 = new javax.swing.JTextField();

        jTextField3 = new javax.swing.JTextField();

        jTextField4 = new javax.swing.JTextField();

        jButton1 = new javax.swing.JButton();

        jTextField5 = new javax.swing.JTextField();

        jScrollPane1 = new javax.swing.JScrollPane();

        jTable1 = new javax.swing.JTable();

        jButton2 = new javax.swing.JButton();

        jButton3 = new javax.swing.JButton();

        jButton4 = new javax.swing.JButton();

        jMenuItem1.setText("modificar");

        jMenuItem1.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                jMenuItem1ActionPerformed(evt);

            }

        });

        jPopupMenu1.add(jMenuItem1);

        jMenuItem2.setText("Eliminar");

        jMenuItem2.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                jMenuItem2ActionPerformed(evt);

            }

        });

        jPopupMenu1.add(jMenuItem2);

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText("carreteras mexico");

        jLabel2.setText("Estado");

        jLabel3.setText("Municipio");

        jLabel4.setText("Ciudad");

        jLabel5.setText("Carretera n°");

        jButton1.setText("Ingresar");

        jButton1.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                jButton1ActionPerformed(evt);

            }

        });

        jTextField5.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                jTextField5ActionPerformed(evt);

            }

        });

        jTable1.setModel(new javax.swing.table.DefaultTableModel(

            new Object [][] {

                {null, null, null, null},

                {null, null, null, null},

                {null, null, null, null},

                {null, null, null, null}

            },

            new String [] {

                "Title 1", "Title 2", "Title 3", "Title 4"

            }

        ));

        jTable1.setComponentPopupMenu(jPopupMenu1);

        jScrollPane1.setViewportView(jTable1);

        jButton2.setText("Mostrar");

        jButton2.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                jButton2ActionPerformed(evt);

            }

        });

        jButton3.setText("buscar");

        jButton3.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                jButton3ActionPerformed(evt);

            }

        });

        jButton4.setText("modificar");

        jButton4.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {

                jButton4ActionPerformed(evt);

            }

        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());

        getContentPane().setLayout(layout);

        layout.setHorizontalGroup(

            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

            .addGroup(layout.createSequentialGroup()

                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

                    .addGroup(layout.createSequentialGroup()

                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

                            .addGroup(layout.createSequentialGroup()

                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)

                                    .addComponent(jLabel5)

                                    .addComponent(jLabel4)

                                    .addComponent(jLabel3)

                                    .addComponent(jLabel2))

                                .addGap(39, 39, 39)

                                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

                                    .addComponent(jTextField2)

                                    .addComponent(jTextField3)

                                    .addComponent(jTextField4)

                                    .addComponent(jTextField1)))

                            .addGroup(layout.createSequentialGroup()

                                .addGap(167, 167, 167)

                                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 108, javax.swing.GroupLayout.PREFERRED_SIZE)

                                .addGap(0, 0, Short.MAX_VALUE))

                            .addGroup(layout.createSequentialGroup()

                                .addComponent(jButton2)

                                .addGap(19, 19, 19)

                                .addComponent(jButton3)

                                .addGap(18, 18, 18)

                                .addComponent(jTextField5)))

                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)

                        .addComponent(jButton1))

                    .addGroup(layout.createSequentialGroup()

                        .addContainerGap()

                        .addComponent(jScrollPane1)))

                .addContainerGap())

            .addGroup(layout.createSequentialGroup()

                .addContainerGap()

                .addComponent(jButton4)

                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))

        );

        layout.setVerticalGroup(

            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

            .addGroup(layout.createSequentialGroup()

                .addContainerGap()

                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 22, javax.swing.GroupLayout.PREFERRED_SIZE)

                .addGap(18, 18, 18)

                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)

                    .addComponent(jLabel2)

                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))

                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)

                    .addGroup(layout.createSequentialGroup()

                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)

                        .addGroup(layout.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))

                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)

                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)

                            .addComponent(jLabel4)

                            .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))

                    .addGroup(layout.createSequentialGroup()

                        .addGap(18, 18, 18)

                        .addComponent(jButton1)))

                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)

                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)

                    .addComponent(jLabel5)

                    .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))

                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)

                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)

                    .addComponent(jTextField5, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)

                    .addComponent(jButton2)

                    .addComponent(jButton3))

                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)

                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 133, javax.swing.GroupLayout.PREFERRED_SIZE)

                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)

                .addComponent(jButton4)

                .addGap(17, 17, 17))

        );

        pack();

    }// </editor-fold>

    String Estado="";

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {

       conectar cc=new conectar();

    Connection cn=cc.carreteras();

        try{

            PreparedStatement pst=cn.prepareStatement("INSERT INTO idcarreteras(Estado, Municipio, Ciudad, Carretera) VALUES(?,?,?,?)");

            pst.setString(1,jTextField1.getText());

            pst.setString(2,jTextField2.getText());

            pst.setString(3,jTextField3.getText());

            pst.setString(4,jTextField4.getText());

        int a=pst.executeUpdate();

        if(a>0){

            JOptionPane.showMessageDialog(null,"Registro exitoso");

             mostrardatos("");

        }

        else{

             JOptionPane.showMessageDialog(null,"Error al agregar");

        }

        }catch(Exception e){

        }

        // TODO add your handling code here:

    }

    private void jTextField5ActionPerformed(java.awt.event.ActionEvent evt) {

      mostrardatos(jTextField5.getText());

        // TODO add your handling code here:

    }

    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {

        // TODO add your handling code here:

    }

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {

     mostrardatos("");   // TODO add your handling code here:

    }

    private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {

       int fila=jTable1.getSelectedRow();

    if(fila>=0){

        jTextField1.setText(jTable1.getValueAt(fila,0).toString());

        jTextField2.setText(jTable1.getValueAt(fila,1).toString());

        jTextField3.setText(jTable1.getValueAt(fila,2).toString());

        jTextField4.setText(jTable1.getValueAt(fila,3).toString());

        Estado = jTable1.getValueAt(fila,0).toString();

    }

    else{

        JOptionPane.showMessageDialog(null,"No se encontro fila");

    }

        // TODO add your handling code here:

    }

    private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {

          conectar cc=new conectar();

Connection cn=cc.carreteras();

try{

PreparedStatement pst=cn.prepareStatement("UPDATE Estadocarretera SET Municipio='"+jTextField2.getText()+"', Eatado='"+jTextField1.getText()+"' WHERE Estado='"+Estado+"' ");

Estado=jTextField1.getText();

pst.executeUpdate();

mostrardatos("");

}catch(Exception e){

    System.out.print(e.getMessage());

}  // TODO add your handling code here:

    }

    private void jMenuItem2ActionPerformed(java.awt.event.ActionEvent evt) {

              conectar cc=new conectar();

Connection cn=cc.carreteras();

int fila=jTable1.getSelectedRow();

String cod="";

cod=jTable1.getValueAt(fila,0).toString();

try{

PreparedStatement pst=cn.prepareStatement("DELETE FROM idcarreteras WHERE id='"+cod+"'");

pst.executeUpdate();

mostrardatos("");// TODO add your handling code here:

} catch (Exception e){

}

// TODO add your handling code here:

    }

    /**

     * @param args the command line arguments

     */

    public static void main(String args[]) {

        /* Set the Nimbus look and feel */

        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">

        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.

         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html

         */

        try {

            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {

                if ("Nimbus".equals(info.getName())) {

                    javax.swing.UIManager.setLookAndFeel(info.getClassName());

                    break;

                }

            }

        } catch (ClassNotFoundException ex) {

            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

        } catch (InstantiationException ex) {

            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

        } catch (IllegalAccessException ex) {

            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

        } catch (javax.swing.UnsupportedLookAndFeelException ex) {

            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);

        }

        //</editor-fold>

        /* Create and display the form */

        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {

                new NewJFrame().setVisible(true);

            }

        });

    }

    // Variables declaration - do not modify

    private javax.swing.JButton jButton1;

    private javax.swing.JButton jButton2;

    private javax.swing.JButton jButton3;

    private javax.swing.JButton jButton4;

    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.JMenuItem jMenuItem1;

    private javax.swing.JMenuItem jMenuItem2;

    private javax.swing.JPopupMenu jPopupMenu1;

    private javax.swing.JScrollPane jScrollPane1;

    private javax.swing.JTable jTable1;

    private javax.swing.JTextField jTextField1;

    private javax.swing.JTextField jTextField2;

    private javax.swing.JTextField jTextField3;

    private javax.swing.JTextField jTextField4;

    private javax.swing.JTextField jTextField5;

    // End of variables declaration

     private void mostrardatos(String string) {

        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

    }