Name this program StuPreIPv$6)$ Each network device must be assigned an IP address. An IPv$6$

$($IP address version $6)$ address is represented in the preferred format as eight groups of four

hexadecimal digits. A hexadecimal digit may be $0$ ~ $9$ or a ~ f $($or A ~ F$).$ The groups are separated

by colons $($:$).$ An example of an IPv$6$ address in the preferred format is:

$2001$:$0$db$8$:$85$a$3$:$0000$:$0000$:$8$a$2$e:$0370$:$7001$

Write a method to decide whether a string contains a valid IPv$6$ address in the preferred format $($each

h represents a hexadecimal digit$)$:

hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh

For this assignment, your method must loop through individual characters in the string. Approaches

using regular expression and$/$or API classes like Pattern, Matcher will receive zero credit.

Your program $($i$.$e$.$ your class$)$ will have two methods, the actual method and a main$().$ Start with a

method stub like the one below. The main$()$ will be used to test your method with different data $($see

ch$6\mathrm{.}7$ Unit testing$).$

$//$ Returns true if the string parameter contains a valid IPv$6$

$//$ address in the preferred format. Otherwise returns false.

public static boolean isValidPreferFormatIpv$6($String address$)\{$

return false;

$\}$

$//$ for unit testing: test the method with different arguments

public static void main$($String$[]$ args$)\{$

System.out.println$("$Testing started $...")$;

String str; $//$ store a test string

boolean expected; $//$ expected result of true or false for the test string

str $=""$; $//$ an invalid string

expected $=$ false;

if $($isValidPreferFormatIpv$6($str$)!=$ expected$)$

System.out.println$("$Test: $"+$ str $+"-$ failed"$)$;

str $="0123$:$4567$:$89$ab:cdef:$0123$:$4567$:$89$ab:cDEf"; $//$ valid

expected $=$ true;