AlertDialog ANDROID accent error

Personal to having problems with AlertDialog , when opened it displays the accentuations and neither cedilla, in place appears that old "triangle with interrogation inside". What to do to resolve?

public void alertaInternet(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

    // Definindo Dialog Title
    alertDialog.setTitle("Sem conexão a internet!");

    // Definindo Dialog Message
    alertDialog.setMessage("O aplicativo precisa de conexão a internet para prosseguir.");

    // Ao pressionar o botão OK
    alertDialog.setNegativeButton("Fechar", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });

    // Mostrando Alert Message
    alertDialog.show();
}