Problema com o JTDS

public class Conexao 
{
    
    private static String driver = "net.sourceforge.jtds.jdbc.Driver";
    private static String banco = "gerenciaRH"; //Nome do Banco criado
    private static String host = "localhost"; //Maquina onde está o banco
    private static String str_conexao = "jdbc:jtds:sqlserver://" + host + ":1433/" + banco; //URL de conexão
    private static String usuario = "sa"; //Usuário do banco
    private static String senha = ""; //Senha de conexão
    private static Connection conexao = null;
    private static Statement state;
    
 public Statement conectar()
 {
   try 
   {
        if (conexao == null || conexao.isClosed()) 
        {
            Class.forName(driver).newInstance();
            conexao = (Connection) DriverManager.getConnection(str_conexao, usuario, senha);
            state = (Statement) conexao.createStatement();
            return state;
        }
        else 
        {
 
            return state;
        }
    }
    catch (ClassNotFoundException e) 
    {
        System.out.println(e);
        return null;
    }
    catch (SQLException e) 
    {
        System.out.println(e);
        return null;
    }
    catch (Exception e)
    {
        System.out.println(state);
        System.out.println(e);
        return null;
    }
}
 public static void fechaConexaoBD () 
 {
    try 
    {
        conexao.close();
    }
    catch (SQLException e) 
    {
        e.printStackTrace();
    }
 }
}