Error in the validation of the CPF

I'm trying to do a validation in the CPF and I'm encountering problems. When I type any number that is not in if , it inserts in the bank normally, but when I type numbers from within if I would like it to display the invalid cpf message and not play to bank, but the most I could do was insert "INVALID CPF !!!" in the bank ... If anyone can help me. I am sending three classes Conexao , Socio and validarCpf .

Class Conexao :

public void CadastrarUsuario() {
    conectarBanco();

    CpfValidacao ver2 = new CpfValidacao();

    try {
        Socio cadastrarNovoSocio = new Socio();
        CpfValidacao ver = new CpfValidacao();

        String sql = ("insert into cadastrousuario values('"
                + cadastrarNovoSocio.getNome() + "','"
                + cadastrarNovoSocio.getEmail() + "','"
                + cadastrarNovoSocio.getDdd() + "','"
                + cadastrarNovoSocio.getTelefoneUsuario() + "','"
                + ver.getValidaCpf()+"')");

        stm.executeUpdate(sql);
        con.close();

    } catch (Exception e) {
        System.out.println("Erro: " + e);

    }
}

Partner Class

public String getCpf() {
    System.out.println("Informe o CPF: ");
    cpf = scan.nextLine();
    return cpf;
}

public void setCpf(String cpf) {
    this.cpf = cpf;
}

Class CpfValidation

public class CpfValidacao {
    private String validaCpf;

    public void fecharConexao(){
        Conexao teste = new Conexao();
        teste.desconectarBanco();
    }
    public String getValidaCpf() {
        Socio validar = new Socio();
        validaCpf = validar.getCpf();

        if (validaCpf.equals("11111111111") || validaCpf.equals("22222222222")
                || validaCpf.equals("33333333333") || validaCpf.equals("44444444444")
                || validaCpf.equals("55555555555") ||validaCpf.equals("66666666666")
                || validaCpf.equals("77777777777") ||validaCpf.equals("88888888888")
                || validaCpf.equals("99999999999") ||validaCpf.length() != 11) {

            fecharConexao();
            return "CPF INVÁLIDO!!!";
        }
        return validaCpf;
    }
    public void fecharConexao(String validaCpf) {
        this.validaCpf = validaCpf;
    }
}