Apparently there is a method that takes a char and returns a char: http://download.oracle.com/javase/6/docs/api/java/lang/Character.html#toLowerCase(char)
toLowerCase() is a static method of Character class. So, you will have to use the class name to invoke the method and pass the character which you want to convert to lower case.
Usage--> Character.toLowerCase()
Other static methods are-->
toUpperCaseisLowerCaseisUpperCaseisDigitisAlphabetic