@Override
            boolean check(char ch) {
                return Character.isLowerCase(ch);
            }
ctype extension
documentation: http://us1.php.net/manual/ru/book.ctype.php

 Notice: supports UNICODE
exts/jphp-zend-ext/src/main/java/org/develnext/jphp/zend/ext/standard/CTypeFunctions.java