关于正则表达式的一道面试题

这里写代码片

import java.util.Arrays;

public class ip_test {

    /** * "172.25.27.1 3.25.118.32 105.38.225.12" * 对上面字符串把ip地址切割出来进行排序 * */
    public static void main(String[] args) {
        String ip = "172.25.27.1 3.25.118.32 105.38.225.12";
        System.out.println("原字符串:"+ip);
        ip=ip.replaceAll("(d+)","00$1");
        System.out.println("先补0:"+ip);
        ip=ip.replaceAll("0*(d{3})","$1");
        System.out.println("留三位:"+ip);
        String[] new_ip = ip.split(" +");
        // System.out.println(new_ip);//这样打印的是字符串数组的首地址

        Arrays.sort(new_ip);

        System.out.println("去0再排序后:");
        for (String string : new_ip) {

            System.out.println(string.replaceAll("0*([0-9]{1,2})","$1"));

        }

    }

}