### Question:
IpAddressUtils { public static long getNetworkAddress(String cidr) { String[] array = StringUtils.split(cidr, "/", 2); int prefix = Integer.parseInt(array[1]); return getNetworkAddress(array[0], prefix); }  static long parse(String ipAddress); static String format(long ipAddress); static long getNetworkAddress(String cidr); static long getNetworkAddress(String ipAddress, int prefix); static long getNetworkAddress(long ipAddress, int prefix); static long getBroadcastAddress(String cidr); static long getBroadcastAddress(String ipAddress, int prefix); static long getBroadcastAddress(long ipAddress, int prefix);  }### Answer:
@Test public void testGetNetworkAddress() { assertEquals("0.0.0.0", IpAddressUtils.format(IpAddressUtils.getNetworkAddress("192.168.1.5/0"))); assertEquals("192.0.0.0", IpAddressUtils.format(IpAddressUtils.getNetworkAddress("192.168.1.5/8"))); assertEquals("192.168.0.0", IpAddressUtils.format(IpAddressUtils.getNetworkAddress("192.168.1.5/16"))); assertEquals("192.168.1.0", IpAddressUtils.format(IpAddressUtils.getNetworkAddress("192.168.1.5/24"))); assertEquals("192.168.1.5", IpAddressUtils.format(IpAddressUtils.getNetworkAddress("192.168.1.5/32"))); }