question: private boolean isOnline ( ) { String port = HOST_IP . contains ( ":" ) ? HOST_IP . substring ( HOST_IP . indexOf ( ':' ) + 1 ) : "80" ; String ip = HOST_IP . contains ( ":" ) ? HOST_IP . substring ( 0 , HOST_IP . indexOf ( ':' ) ) : HOST_IP ; Socket socket = null ; try { SocketAddress sockaddr = new InetSocketAddress ( ip , new Integer ( port ) ) ; socket = new Socket ( ) ; socket . connect ( sockaddr , 5000 ) ; } catch ( NumberFormatException | IOException e ) { return false ; } finally { try { if ( socket != null ) { socket . close ( ) ; } } catch ( IOException ex ) { } } return true ; }
target:  Internal function to check, if device is available and answers to ping requests.