验证IP地址，字符串匹配str.matches("[0-9a-fA-F]*"),按字符匹配

 

import java.util.*;

public class Solution {

    /**

     * 验证IP地址

     * @param IP string字符串 一个IP地址字符串

     * @return string字符串

     */

    public String solve (String IP) {

        //判断可能是IPV4，子串转化为数字，范围是否在0-255，且不以为0开始

        //判断可能是IPV6，判断子串是否匹配[0-9a-fA-F],是否最多4位，是否有多余的0

        //既不是IPV4，又不是IPV6

        if(IP.indexOf(".")!=-1){

            String[] subs = IP.split("\\.");

            if(subs.length!=4){

                return "Neither";

            }

            for(int i=0; i<4; i++){

                if(!subs[i].matches("[0-9]*")){

                    return "Neither";

                }

                if(subs[i].startsWith("0")){

                    return "Neither";

                }

                int tmp = Integer.parseInt(subs[i]);

                if(tmp>255 || tmp<=0 ){

                    return "Neither";

                } 

                if(i==3){

                    return "IPv4";

                }

            }

        }

        else if(IP.indexOf(":")!=-1){

            String[] subs = IP.split(":");

            if(subs.length!=8 ||IP.endsWith(":")){

                return "Neither";

            }

            for(int i=0; i<8; i++){

                if(!subs[i].matches("[0-9a-fA-F]*")){

                    return "Neither";

                }

                if(subs[i].length()>4){

                    return "Neither";

                }

                if(subs[i].startsWith("00")|| subs[i].startsWith("000")|| subs[i].startsWith("0000")){

                    return "Neither";

                }

                if(subs[i].equals("")){

                    return "Neither";

                }

                int tmp = Integer.parseInt(subs[i],16);

                if(tmp>65535 || tmp<0 ){

                    return "Neither";

                } 

                if(i==7){

                    return "IPv6";

                }

            }

        }else{

            return "Neither";

        }

        return "Neither";

    }

}