String capitalize - better way

Question

What method of capitalizing is better?

mine:

char[] charArray = string.toCharArray();
charArray[0] = Character.toUpperCase(charArray[0]);
return new String(charArray);

or

commons lang - StringUtils.capitalize:

return new StringBuffer(strLen)
            .append(Character.toTitleCase(str.charAt(0)))
            .append(str.substring(1))
            .toString();

I think mine is better, but i would rather ask.

Answer 1

I guess your version will be a little bit more performant, since it does not allocate as many temporary String objects.

I'd go for this (assuming the string is not empty):

StringBuilder strBuilder = new StringBuilder(string);
strBuilder.setCharAt(0, Character.toUpperCase(strBuilder.charAt(0))));
return strBuilder.toString();

However, note that they are not equivalent in that one uses toUpperCase() and the other uses toTitleCase().

From a forum post:

Titlecase <> uppercase
Unicode defines three kinds of case mapping: lowercase, uppercase, and titlecase. The difference between uppercasing and titlecasing a character or character sequence can be seen in compound characters (that is, a single character that represents a compount of two characters).

For example, in Unicode, character U+01F3 is LATIN SMALL LETTER DZ. (Let us write this compound character using ASCII as "dz".) This character
uppercases to character U+01F1, LATIN CAPITAL LETTER DZ. (Which is
basically "DZ".) But it titlecases to to character U+01F2, LATIN CAPITAL
LETTER D WITH SMALL LETTER Z. (Which we can write "Dz".)

character uppercase titlecase
--------- --------- ---------
dz        DZ        Dz

Answer 2

If I were to write a library, I'd try to make sure I got my Unicode right beofre worrying about performance. Off the top of my head:

int len = str.length();
if (len == 0) {
    return str;
}
int head = Character.toUpperCase(str.codePointAt(0));
String tail = str.substring(str.offsetByCodePoints(0, 1));
return new String(new int[] { head }).concat(tail);

(I'd probably also look up the difference between title and upper case before I committed.)