Conectando com hsqldb me ajudem por favor

package utilitarios; 
import java.sql.*; 
import javax.swing.*; 

public class conexao 
{ 
final private String driver = "org.hsqldb.jdbcDriver"; 
final private String url = "jdbc:hsqldb:file:C:/banco/bd"; 
final private String usuario = "sa"; 
final private String senha = ""; 
private Connection conecta; 
public Statement statement; 
public ResultSet resultset; 

public boolean conecta() 
{ 
boolean result = true; 
try 
{ 
Class.forName(driver); 
conecta = DriverManager.getConnection(url, usuario, senha); 
JOptionPane.showMessageDialog(null, "Conectado"); 
} 
catch (ClassNotFoundException Driver) 
{ 
JOptionPane.showMessageDialog(null, "Driver nao localizado: "+Driver); 
result = false; 
} 
catch(SQLException Fonte) 
{ 
JOptionPane.showMessageDialog(null, "Deu erro na conecao com a fonte de dados "+Fonte); 
result = false; 
} 
return result; 
} 

public void desconecta() 
{ 
boolean result = true; 
try 
{ 
conecta.close(); 
JOptionPane.showMessageDialog(null, "Danco Fechado"); 
} 
catch (SQLException erroSQL) 
{ 
JOptionPane.showMessageDialog(null, "Nao foi possivel fechar o banco de dados"+erroSQL.getMessage()); 
result = false; 
} 

} 

public void executaSQL(String sql) 
{ 
try 
{ 
statement = conecta.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY); 
resultset = statement.executeQuery(sql); 
} 
catch (SQLException sqlex) 
{ 
JOptionPane.showMessageDialog(null, sqlex); 

} 

} 
}

import java.sql.SQLException; 
import javax.swing.JOptionPane; 
import utilitarios.conexao; 
public class Tela_Principal extends javax.swing.JFrame { 

conexao con_banco; 
public Tela_Principal() { 
initComponents(); 
con_banco = new conexao(); 
con_banco.conecta(); 
} 
// <editor-fold defaultstate="collapsed" desc=" Generated Code "> 
private void initComponents() { 
jdbcDriver1 = new org.hsqldb.jdbcDriver(); 
botao_salvar = new javax.swing.JButton(); 
jLabel1 = new javax.swing.JLabel(); 
tf_conteudo = new javax.swing.JTextField(); 

setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 
botao_salvar.setText("jButton1"); 
botao_salvar.addActionListener(new java.awt.event.ActionListener() { 
public void actionPerformed(java.awt.event.ActionEvent evt) { 
botao_salvarActionPerformed(evt); 
} 
}); 

jLabel1.setText("dados"); 

tf_conteudo.setText("jTextField1"); 

javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); 
getContentPane().setLayout(layout); 
layout.setHorizontalGroup( 
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
.addGroup(layout.createSequentialGroup() 
.addContainerGap() 
.addComponent(jLabel1) 
.addGap(16, 16, 16) 
.addComponent(tf_conteudo, javax.swing.GroupLayout.PREFERRED_SIZE, 204, javax.swing.GroupLayout.PREFERRED_SIZE) 
.addGap(19, 19, 19) 
.addComponent(botao_salvar) 
.addContainerGap(49, Short.MAX_VALUE)) 
); 
layout.setVerticalGroup( 
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
.addGroup(layout.createSequentialGroup() 
.addGap(20, 20, 20) 
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
.addComponent(tf_conteudo, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
.addComponent(jLabel1) 
.addComponent(botao_salvar)) 
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)) 
); 
pack(); 
}// </editor-fold> 

private void botao_salvarActionPerformed(java.awt.event.ActionEvent evt) { 
/* ================================ */
try 
{ 
String sqlinsert = "INSERT INTO TESTE (NOME) VALUES ('"+tf_conteudo.getText()+"')"; 
con_banco.statement.executeUpdate(sqlinsert); 
} 
catch (SQLException erro) 
{ 
JOptionPane.showMessageDialog(null, erro); 
} 
} 
/* ================================ */
public static void main(String args[]) { 
java.awt.EventQueue.invokeLater(new Runnable() { 
public void run() { 
new Tela_Principal().setVisible(true); 
} 
}); 
} 

// Variables declaration - do not modify 
private javax.swing.JButton botao_salvar; 
private javax.swing.JLabel jLabel1; 
private org.hsqldb.jdbcDriver jdbcDriver1; 
private javax.swing.JTextField tf_conteudo; 
// End of variables declaration 

}