question: public static int toIPv4Address ( String ipAddress ) { if ( ipAddress == null ) throw new IllegalArgumentException ( "Specified IPv4 address must" + "contain 4 sets of numerical digits separated by periods" ) ; String [ ] octets = ipAddress . split ( "\\." ) ; if ( octets . length != 4 ) throw new IllegalArgumentException ( "Specified IPv4 address must" + "contain 4 sets of numerical digits separated by periods" ) ; int result = 0 ; for ( int i = 0 ; i < 4 ; ++ i ) { int oct = Integer . valueOf ( octets [ i ] ) ; if ( oct > 255 || oct < 0 ) throw new IllegalArgumentException ( "Octet values in specified" + " IPv4 address must be 0 <= value <= 255" ) ; result |= oct << ( ( 3 - i ) * 8 ) ; } return result ; }
target:  Accepts an IPv4 address of the form xxx.xxx.xxx.xxx, ie 192.168.0.1 and returns the corresponding 32 bit integer.