Solution for JAVA with explanation:

Scanner scan = new Scanner(System.in); int n =scan.nextInt(); scan.nextLine();

String input = "";

    Pattern ipv4 = Pattern.compile("(([0]?[0-9]?[0-9]|[1][0-9][0-9]|[2][0-5][0-5])(\\.)){3}([0]?[0-9]?[0-9]|[1][0-9][0-9]|[2][0-5][0-5])");

    Pattern ipv6 = Pattern.compile("([a-f\\d]{1,4}(:){1}){7}[a-f\\d]{1,4}");
Matcher m;

for(int i=0;i<n;i++){
    input = scan.nextLine();
    m = ipv4.matcher(input);
    if(m.matches()){
        System.out.println("IPv4");
    }
    else {
        m = ipv6.matcher(input);
        if(m.matches()){
            System.out.println("IPv6");
        }
        else {
            System.out.println("Neither");
        }
    }
    input = "";
}

scan.close();