Mine

/* By Aftermath
For all players:
If player is not null
Cast to client
If client's ip equals the connecting ip
close the socket*/

for(int i = 0; i < playerHandler.players.length; i++) {
    if(playerHandler.players[i] == null) break;
    if(((client)playerHandler.players[i]).connectedFrom.equals(connectingHost)) s.close();
}