You can do with following code, I have tested and It's working perfect.
String value1 = "Total Records to be SYNC : ";
String value2 = "\nDo you want sync all records...!";
String valueFromEdittext = edittext.getText().toString();
String finalValue = value1 + valueFromEdittext + value2;
Spannable WordtoSpan = new SpannableString(finalValue);
WordtoSpan.setSpan(new ForegroundColorSpan(Color.RED), value1.length(), (value1 + valueFromEdittext).length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
mTextView.setText(WordtoSpan);