The fielder at the front of the line then becomes the batter. If the batter hits a line drive or pop-up to the fielders, whoever catches the ball, regardless of their position in the line, becomes the new batter; the batter moves to the end of the line.
The first player in the batting order becomes the batter. If the batter hits a ball that is caught by another player on defense, that player takes over as the new batter; the original batter moves to the end of the lineup.