The Catcher In The Rye, Ch. 3

In chapter 3 in The Catcher In The Rye, we find out that he lives in a dorm with someone else who seems to have a pretty close relationship with. There's Ackley, which lives across the hall from Holden, who always enters Holden's dorm room unannounced. Ackley clearly shows a dislike on Holden's roommate, Stradlater.