Why was Jim hiding in the apple barrel in the story Treasure Island?

Jim actually climbed into the apple barrel because he wanted an apple, after which, he fell asleep He was forced to keep hidden when Silver and another man began to speak. Whatever they were saying caused Jim to keep himself hidden.

Now, just after sundown, when all my work was over and I was on my way to my berth, it occurred to me that I should like an apple. I ran on deck. The watch was all forward looking out for the island. The man at the helm was watching the luff of the sail and whistling away gently to himself, and that was the only sound excepting the swish of the sea against the bows and around the sides of the ship.

In I got bodily into the apple barrel, and found there was scarce an apple left; but sitting down there in the dark, what with the sound of the waters and the rocking movement of the ship, I had either fallen asleep or was on the point of doing so when a heavy man sat down with rather a clash close by. The barrel shook as he leaned his shoulders against it, and I was just about to jump up when the man began to speak. It was Silver's voice, and before I had heard a dozen words, I would not have shown myself for all the world, but lay there, trembling and listening, in the extreme of fear and curiosity, for from these dozen words I understood that the lives of all the honest men aboard depended upon me alone.