题解 | #验证IP地址#

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) {
        // write code here
        if(IP == null || IP.length() < 1){
            return "Neither";
        }
        char[] chars = IP.toCharArray();
            //1.先判断是 v4还是v6
        boolean v4Type = false;
        for(char item : chars){
            if(item == '.'){
                v4Type = true;
                break;
            }else if(item ==':'){
                v4Type = false;
                break;
            }
        }
        return v4Type ? 
            (isV4Validate(IP) ? "IPv4" : "Neither")
            : (isV6Valiedate(IP) ? "IPv6": "Neither");
    }
    
    private boolean isV4Validate(String ip){
        String[] data = ip.split("\\.");
        if(data.length != 4){
            return false;
        }
        for(String item: data){
            if(item.length() >1 && item.startsWith("0")){
                return false;
            }
            try{
                int val = Integer.parseInt(item);
                if(!(val >=0 && val <= 255)){
                    return false;
                }
            }catch(NumberFormatException e){
                return false;
            }
        }
        return true;
        
    }
    
    private boolean isV6Valiedate(String ip){
        char[] data = ip.toCharArray();
        int count = 0;
        for(char item :data){
            if(item == ':'){
                if(count >4 || count == 0){
                    return false;
                }
                count = 0;
            }else if(  !( (item >= '0' && item <= '9') || (item>='a' && item <= 'f') || (item >= 'A' && item <= 'F') )){
                return false;
            }else{
                count ++;
            }
            
        }
        return true;
    }
    
    
    
}