Introduction - If you have any usage issues, please Google them yourself
Write a program HostLookup.java, complete the host domain name and IP address query:
(1) if the user enters the domain name, the program is requested to return the corresponding IP address
(2) if the user enters the IP address, the program is requested to return its corresponding domain name
(3) write a method that can effectively detect whether an input string is an IP address and call authentication in HostLookup.java.