I'm noticing a trend with String methods

I've noticed that with seemingly all of the string methods I use I am able to call the method directly off the string object it's self, often without having to pass in an argument. eg example.toLowerCase(); Where as when working with chars and ints I have to call the method off the wrapper class Integer or Character then pass the object I want to work with in as an argument eg Character.isLetter(guess);

I have also noticed that string is the only type that uses an upper case first letter when declaring objects and I suspect it has a lot to do with this. I remember Craig touched on this very early on saying something like "String is different to the other types as it's the only one we don't really use the primitive type for" or something like that but didn't go into it as it was way above my head at the time.

Am I talking any sense? I'm the kind of guy who generally doesn't like moving on and leaving some things unlearned till a later time. Can someone explain why String is unique in this way or is it way above my current learning?