题解 | 验证IP地址

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 验证IP地址
     * @param IP string字符串 一个IP地址字符串
     * @return string字符串
     */
    final static String strIP6 = "0123456789ABCDEFabcdef";
    final static String strIp4 = "0123456789";

    // IPv4,   IPv6,   Neither

    static  public String solve(String IP) {

        boolean b = checkIsIpv4(IP);
        if (b) {
            return "IPv4";
        }
        boolean c = checkIsIpv6(IP);
        if (c) {
            return "IPv6";
        }
        return "Neither";
    }


    public static boolean checkIsIpv6(String IP) {
        if(IP.endsWith(":")){
            return false;
        }
        String[] split = IP.split(":");
        if (split.length != 8) {
            return false;
        }

        for (String str : split) {
            char[] charArray = str.toCharArray();
            for (int i = 0; i < charArray.length; i++) {
                //校验字符
                if (strIP6.indexOf(charArray[i]) == -1) {
                    return false;
                }
            }
            if (str.isEmpty()) {
                return false;
            }
            if (str.length() > 4) {
                return false;
            }
             if (str.startsWith("00")) {
                return false;
            }
        }
        return true;
    }


    //校验是否是IPv4
    public static boolean checkIsIpv4(String IP) {
        String[] split = IP.split("\\.");
        if (split.length != 4) {
            return false;
        }
        for (String str : split) {
            char[] charArray = str.toCharArray();
            for (int i = 0; i < charArray.length; i++) {
                //校验字符
                if (strIp4.indexOf(charArray[i]) == -1) {
                    return false;
                }
            }
            if (str.isEmpty()) {
                return false;
            }
            if (str.startsWith("0") && str.length() > 1) {
                return false;
            }

            int num = Integer.parseInt(str);
            if (num > 255) {
                return false;
            }
        }
        return true;
    }
}