final byte MIN_NUMPLAYERS = 2;
final byte MAX_NUMPLAYERS = 8;
int numPlayers;
do {
    System.out.printf("How many players? (%d-%d) ", MIN_NUMPLAYERS, MAX_NUMPLAYERS);
    numPlayers = keyboard.nextInt();
}while(numPlayers < MIN_NUMPLAYERS || numPlayers > MAX_NUMPLAYERS);