IP判断 （Java代码）

解题思路:

注意事项:

参考代码:

package Ccode;

import java.util.Scanner;
import java.util.regex.Pattern;

public class IP_panduan {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        while (scanner.hasNext()) {
            boolean flag=false;
            String s=scanner.nextLine();
            Pattern pattern = Pattern.compile("[0-9]*");//判断是否是数字
            if (s.length()>30) break;
            if (s.contains(" "))break;//判断是否有空格
            if (s.equals("End of file")) break;//判断是否结束
            String x[] = s.split("\\.");//将输入字符串分离为ABCD形式
            int i,j;
            for(i=0,j=0;i<x.length&&j<x[i].length();i++) {
                char num[] = x[i].toCharArray();//把字符串转换为字符数组
                //System.out.println(Integer.parseInt(x[i]));
                if (!Character.isDigit(num[j])){
                    flag=false;
                    break;
                }

                if (Integer.parseInt(x[i])>255||Integer.parseInt(x[i])<0){

                    flag=false;
                    break;
                }
                else
                    flag=true;
                }
                if (flag)
                    System.out.println("Y");
                else
                    System.out.println("N");
    }
    }

}