SpannableStringBuilder - BOLD or NORMAL text formatting function

Question

I know this is a simple question but your answer would mean a lot to me, so thank you in advance. What would a function look like that could click the formating button when the text is marked and the function performs bolding or returns the text as normal? Please help me.

                    formating.setOnClickListener(new View.OnClickListener() {
                        public void onClick(View v) {
                            Spannable spannableString = new SpannableStringBuilder(editText.getText());
                            spannableString.setSpan(new StyleSpan(Typeface.BOLD),
                                    editText.getSelectionStart(),
                                    editText.getSelectionEnd(),
                                    0);

                            editText.setText(spannableString);
                        }
                    });