Well, in Symbian C++ there are many types for storing strings. TDesC is a parent type of them. And "Des" actually abbreviates "descriptor", this is how Symbian C++ refers to bounded character and byte arrays.
However for your actual question: in Java, java.lang.String is the string type, and length() is the method for getting the length of a string. Would you really write
? Or would you rather have a variable of type String, and invoke length() on that variable? Now in my example code, "descriptor" is the name of such variable.
Of course you can imagine CharSequence in place of String, that also has a length() method.