String.toLowerCase.java

public String toLowerCase(Locale locale) {
    if (locale == null) {
        throw new NullPointerException();
    }

    int     firstUpper;

    /* Now check if there are any characters that need to be changed. */
    scan: {
        for (firstUpper = 0 ; firstUpper < count; ) {
            char c = value[offset+firstUpper];
            if ((c >= Character.MIN_HIGH_SURROGATE) &&
                (c <= Character.MAX_HIGH_SURROGATE)) {
                int supplChar = codePointAt(firstUpper);
                if (supplChar != Character.toLowerCase(supplChar)) {
                    break scan;
                }
                firstUpper += Character.charCount(supplChar);
            } else {
                if (c != Character.toLowerCase(c)) {
                    break scan;
                }
                firstUpper++;
            }
        }
        return this;
    }

    char[]  result = new char[count];
    int     resultOffset = 0;  /* result may grow, so i+resultOffset
                                * is the write location in result */

    /* Just copy the first few lowerCase characters. */
    System.arraycopy(value, offset, result, 0, firstUpper);

    String lang = locale.getLanguage();
    boolean localeDependent =
        (lang == "tr" || lang == "az" || lang == "lt");
    char[] lowerCharArray;
    int lowerChar;
    int srcChar;
    int srcCount;
    for (int i = firstUpper; i < count; i += srcCount) {
        srcChar = (int)value[offset+i];
        if ((char)srcChar >= Character.MIN_HIGH_SURROGATE &&
            (char)srcChar <= Character.MAX_HIGH_SURROGATE) {
            srcChar = codePointAt(i);
            srcCount = Character.charCount(srcChar);
        } else {
            srcCount = 1;
        }
        if (localeDependent || srcChar == '\u03A3') { // GREEK CAPITAL LETTER SIGMA
            lowerChar = ConditionalSpecialCasing.toLowerCaseEx(this, i, locale);
        } else {
            lowerChar = Character.toLowerCase(srcChar);
        }
        if ((lowerChar == Character.ERROR) ||
            (lowerChar >= Character.MIN_SUPPLEMENTARY_CODE_POINT)) {
            if (lowerChar == Character.ERROR) {
                lowerCharArray =
                    ConditionalSpecialCasing.toLowerCaseCharArray(this, i, locale);
            } else if (srcCount == 2) {
                resultOffset += Character.toChars(lowerChar, result, i + resultOffset) - srcCount;
                continue;
            } else {
                lowerCharArray = Character.toChars(lowerChar);
            }

            /* Grow result if needed */
            int mapLen = lowerCharArray.length;
            if (mapLen > srcCount) {
                char[] result2 = new char[result.length + mapLen - srcCount];
                System.arraycopy(result, 0, result2, 0,
                    i + resultOffset);
                result = result2;
            }
            for (int x=0; x<mapLen; ++x) {
                result[i+resultOffset+x] = lowerCharArray[x];
            }
            resultOffset += (mapLen - srcCount);
        } else {
            result[i+resultOffset] = (char)lowerChar;
        }
    }
    return new String(0, count+resultOffset, result);
}