### Question:
NetUtils { public static String getHostName(String address) { try { int i = address.indexOf(':'); if (i > -1) { address = address.substring(0, i); } String hostname = hostNameCache.get(address); if (hostname != null && hostname.length() > 0) { return hostname; } InetAddress inetAddress = InetAddress.getByName(address); if (inetAddress != null) { hostname = inetAddress.getHostName(); hostNameCache.put(address, hostname); return hostname; } } catch (Throwable e) { } return address; }  static int getRandomPort(); static int getAvailablePort(); static int getAvailablePort(int port); static boolean isValidAddress(String address); static boolean isLocalHost(String host); static boolean isAnyHost(String host); static boolean isInvalidLocalHost(String host); static boolean isValidLocalHost(String host); static InetSocketAddress getLocalSocketAddress(String host, int port); static String getLocalHost(); static String filterLocalHost(String host); static InetAddress getLocalAddress(); static String getLogHost(); static String getHostName(String address); static String getIpByHost(String hostName); static String toAddressString(InetSocketAddress address); static InetSocketAddress toAddress(String address); static String toURL(String protocol, String host, int port, String path); static final String LOCALHOST; static final String ANYHOST; }### Answer:
@Test public void getHostName() throws Exception { Assert.assertEquals("localhost", NetUtils.getHostName("localhost")); Assert.assertEquals("127.0.0.1", NetUtils.getHostName("127.0.0.1")); }