Is there a regex replacement term for the uppercase/lowercase version of a back reference? [duplicate]

Question

Suppose I want to change a lowercase string to "title case"; where the first letter of every word is capitalized. Can this be done using a single call to replaceAll() by using a modifier in the replacement expression?

For example,

str = str.replaceAll("\\b(\\S)", "???$1");

Where "???" is some expression that folds the case of the next letter.

I have seen this is other tools (like textpad), where \U will fold the next letter to uppercase.

?

Answer 1

Not possible with replaceAll. But you can use regex and split:

public String titleTextConversion(String text) {
    String[] words = text.split("(?<=\\W)|(?=\\W)");
    StringBuilder sb = new StringBuilder();
    for (String word : words) {
        if (word.length() > 0)
            sb.append(word.substring(0, 1).toUpperCase()).append(word.substring(1).toLowerCase());
    }
    return sb.toString();
}