Method toUpperCase

guava/src/com/google/common/base/Ascii.java:455–470

Returns a copy of the input string in which all {@linkplain #isLowerCase(char) lowercase ASCII characters} have been converted to uppercase. All other characters are copied without modification.

(String string)

   * modification.
   */
  public static String toUpperCase(String string) {
    int length = string.length();
    for (int i = 0; i < length; i++) {
      if (isLowerCase(string.charAt(i))) {
        char[] chars = string.toCharArray();
        for (; i < length; i++) {
          char c = chars[i];
          if (isLowerCase(c)) {
            chars[i] = (char) (c ^ CASE_MASK);
          }
        }
        return String.valueOf(chars);
      }
    }
    return string;
  }

  /**
   * Returns a copy of the input character sequence in which all {@linkplain #isLowerCase(char)