I think he's an xNFP, leaning more towards I than E by just a little. I adore that book, and read it six times within the first year of picking it up, and I did my english research project on it when I was at school and got full marks. (I am not saying that to say 'whoa I'm awesome!' I just mean I think people *can* have a different perspective to you, and know the book well.)
I'm an NFP and I identified with him, certainly. I think calling him an S is to totally misunderstand him. A huge element of that book is that Holden is confused and lost, since he is asking big questions about the world and not finding answers. Think of the ever famous ducks; Holden is asking questions about them because on an intuitive level he feels a connection with them. He desperately seeks to 'connect' with people, and Mr Antolini is clearly an N and that is a teacher who's had a great deal of influence over him. Holden despises 'phoniness' and part of that is shallowness and convention. Of course he fails to truly grapple with peoples motives, and ironically is a bit of a hypocrite as a result, but I think J.D Salinger wants to portray Holden as someone who in a sense realises he's a hypocrite. He feels lost in the world and isolates himself by feeling different to everyone else and labelling it because of their phoniness. But his insights can be incredibly perceptive -particularly about people - and he obviously has a lot of depth. He loves fiction and getting caught up in another world through reading a book, again that seems fairly NF to me; escapism through literature.
I think he's an NF; he seems to fit the idealist portrait. He's obviously highly traumatised by the death of his younger brother, and has an emotional response to that (smashing all the windows in the garage). He has a strong sense of how the world 'ought' to be, and has a deep caring side which is demonstrated in how he treats his sister and the fact at regular times in the book there are people who he empathises and sympathises with (the Head teachers daughter, Ackley, Jane). Holden really values the nuns for altruistically caring for others, and what he perceives as authenticity; desire for authenticity is very NF.
In terms of I/E, I think it's difficult to tell because Holden is depressed and that has a natural impact on whether or not you appear extroverted. He certainly has extroverted traits; he seeks out the company of others throughout the book, sometimes people he doesn't even know very well, and obviously has a wide circle of acquaintances. However, I think part of that is in hope they will elucidate things for him and help him to understand why he is as he is, and at other times he simply wants distraction from how bad he feels. I think he's possibly an I though, since he's very introspective, wants time alone, reads a lot, sometimes can't be bothered with humanity as a whole, and seeks deep meaningful connections on a one-on-one level. I think he is hesitant to share his inner world with others, which can also be an introverted thing. I am not sure socialising for the sake of socialising would appeal to him. The log cabin fantasy at the end could be seen as an introverted thing, but I think that's his idea of the ultimate way of cutting himself off from humanity in order to avoid pain. There's a great paradox throughout the book; Holden longs for people to understand and accept him, but equally he despises many elements of the human condition and isolates himself from people. He spends the book vacillating between the two, hence E/I being difficult to determine.
I see nobody has questioned if he's a P, I think that's pretty self-evident
I think this book is grossly misunderstood. Teenagers who say 'I love Holden, finally someone who understands me!' and adults who say 'What a whiny brat', in my opinion, miss J.D Salinger's point. I don't think J.D Salinger is endorsing everything Holden says. You're *meant* to recognise that Holden is a bit of a hypocrite and isolating himself from the world through a pseudo-superiority complex. I think you're meant to look beyond that and question why he is so lost, and it particularly relates back to unexpressed grief regarding his brother and other traumatic events. I can genuinely say that 'The Catcher in the Rye' is the only fictional book to change my life, not 'cause I agreed with Holden, but cause I saw elements of himself he was blind to that related to moi.
It's quite pathetic how defensive I get when people criticise Holden Caulfield, I just want to give him a hug.