How is The Catcher in the Rye similar to Through the Tunnel?

J.D. Salinger's novel and Doris Lessing's short story are similar in that they are both concerned with the protagonist's coming of age. Jerry and Holden undergo some painful, self-inflicted episodes of testing themselves physically and psychologically as they begin to move from one stage of development to another. At seventeen, Holden is moving from adolescence toward manhood, and at eleven, Jerry is moving from childhood to adolescence.
Jerry is eager to make his journey; he seeks the company of older boys and strives to emulate their physical prowess by swimming underwater through a tunnel. He suffers humiliation when he can't keep up with them, and he cries. Over the course of his vacation, Jerry has to both conquer his fear and strengthen himself physically to hold his breath long enough to make the swim. He must keep his efforts a secret from his mother because of the danger; she is a widow, and it seems Jerry is all she has.
Holden is less eager to make his journey, but his age makes it inevitable. Like Jerry, Holden suffers some humiliations during the days he spends outside the control of his family. He stands up to Stradlater and is physically humiliated. Like Jerry, his test involves a nosebleed and tears that he must process on his own. Physical pain happens again at the hands of Maurice, the pimp. Like Jerry, Holden feels that he must keep his misadventures a secret from his parents; they, too, have suffered a loss with Allie's death. Holden faces psychological tests as he discovers what he values and what he doesn't. He does not turn to his parents to simply accept what they would tell him. Covert behavior is a factor in the development of most young people, and it is certainly a factor with both Holden and Jerry.
Both boys must learn to navigate a portion of the adult world on their own. Once Holden is able to understand his situation and acknowledge that he must grow up, he is ready to go home and face his family. Jerry does essentially the same thing; when he finally makes the swim, he tells his mother in a roundabout way about his triumph. Both boys have come through a test that is likely to remain known only to themselves.