Mine

alias ifjava { 
  if (java isin $remove($left($address($1,0),$pos($address($1,0),@,1)),*!,@)) { 
    return $true
    halt
  }
  return $false
}
on *:join:#channel: {
  inc %cscan
  if ($ifjava($nick)) { ban -k $chan $nick 9 JAVA users are not permitted to enter this channel }
  if (%cscan > 50) {
    echo -s 4Performing JAVA scan on $chan (automatically after 50 people join)
    var %d = 1
    while (%d <= $nick($chan,0)) {
      if ($ifjava($nick($chan,%d)) { 
        inc %c
        ban -k $chan $nick 9 JAVA users are not permitted to enter this channel 
      }
      inc %d
    }
    echo -s Removed %c people from $+($chan,.)
    echo -s -
    unset %c
  }
}