### Question:
NetUtil { public static boolean isValidIpV4Address(CharSequence ip) { return isValidIpV4Address(ip, 0, ip.length()); } private  NetUtil(); static boolean isIpV4StackPreferred(); static boolean isIpV6AddressesPreferred(); static byte[] createByteArrayFromIpAddressString(String ipAddressString); static String intToIpAddress(int i); static String bytesToIpAddress(byte[] bytes); static String bytesToIpAddress(byte[] bytes, int offset, int length); static boolean isValidIpV6Address(String ip); static boolean isValidIpV6Address(CharSequence ip); static boolean isValidIpV4Address(CharSequence ip); static boolean isValidIpV4Address(String ip); static Inet6Address getByName(CharSequence ip); static Inet6Address getByName(CharSequence ip, boolean ipv4Mapped); static String toSocketAddressString(InetSocketAddress addr); static String toSocketAddressString(String host, int port); static String toAddressString(InetAddress ip); static String toAddressString(InetAddress ip, boolean ipv4Mapped); static String getHostname(InetSocketAddress addr); static final Inet4Address LOCALHOST4; static final Inet6Address LOCALHOST6; static final InetAddress LOCALHOST; static final NetworkInterface LOOPBACK_IF; static final int SOMAXCONN; }### Answer:
@Test public void testIsValidIpV4Address() { for (String host : validIpV4Hosts.keySet()) { assertTrue(host, isValidIpV4Address(host)); } for (String host : invalidIpV4Hosts.keySet()) { assertFalse(host, isValidIpV4Address(host)); } }