code: public static final boolean parseBoolean(CharSequence cs, int beginIndex, int endIndex)
      {
          return 
                  endIndex - beginIndex == 4 &&
                  Character.codePointCount(cs, beginIndex, endIndex) == 4 &&
                  Character.toUpperCase(Character.codePointAt(cs, beginIndex)) == 'T' &&
                  Character.toUpperCase(Character.codePointAt(cs, beginIndex+1)) == 'R' &&
                  Character.toUpperCase(Character.codePointAt(cs, beginIndex+2)) == 'U' &&
                  Character.toUpperCase(Character.codePointAt(cs, beginIndex+3)) == 'E';
      }
docs: Parses the char sequence argument as a boolean. The boolean returned represents
  the value true if the char sequence argument is not null and is equal, ignoring
  case, to the string "true".
  @param cs
  @param beginIndex the index to the first char of the text range.
  @param endIndex the index after the last char of the text range.
  @return
  @throws IllegalArgumentException if input length is not 4.
  @see java.lang.Boolean#parseBoolean(java.lang.String)