string - Converting to upper and lower case in Java

Question

I want to convert the first character of a string to Uppercase and the rest of the characters to lowercase. How can I do it?

Example:

String inputval="ABCb" OR "a123BC_DET" or "aBcd"
String outputval="Abcb" or "A123bc_det" or "Abcd"

Answer 1

Try this on for size:

String properCase (String inputVal) {
    // Empty strings should be returned as-is.

    if (inputVal.length() == 0) return "";

    // Strings with only one character uppercased.

    if (inputVal.length() == 1) return inputVal.toUpperCase();

    // Otherwise uppercase first letter, lowercase the rest.

    return inputVal.substring(0,1).toUpperCase()
        + inputVal.substring(1).toLowerCase();
}

It basically handles special cases of empty and one-character string first and correctly cases a two-plus-character string otherwise. And, as pointed out in a comment, the one-character special case isn't needed for functionality but I still prefer to be explicit, especially if it results in fewer useless calls, such as substring to get an empty string, lower-casing it, then appending it as well.