Normalize a string except ñ

Question

I have the following example code:

String n = "Péña";
n = Normalizer.normalize(n, Normalizer.Form.NFC);

How do I normalize the string n excepting the ñ?

And not only that string, I'm making a form and I want to keep just the ñ's, and everything else without diacritics.

Answer 1

Replace all occurrences of "ñ" with a non-printable character "\001", so "Péña" becomes "Pé\001a". Then call Normalizer.normalize() to decompose the "é" into "e" and a separate diacritical mark. Finally remove the diacritical marks, and convert the non-printable character back to "ñ".

String partiallyNormalize(String string)
{
    string = string.replace('ñ', '\001');
    string = Normalizer.normalize(string, Normalizer.Form.NFD);
    string = string.replaceAll("[\\p{InCombiningDiacriticalMarks}]", "");
    string = string.replace('\001', 'ñ');
    return string;
}

You might also want to upvote the preferred answer to Easy way to remove UTF-8 accents from a string?, where I learned how to remove the diacritical marks.