import java.util.regex.Matcher; import java.util.regex.Pattern; public class test0726 { public static boolean isIp(String ip){ String pattern = "((\\d|[1-9]\\d|1\\d{2}|2[0-4]\\d|25[0-5])\\.){3}(\\d|[1-9]\\d|1\\d{2}|2[0-4]\\d|25[0-5])"; Pattern r = Pattern.compile(pattern); Matcher m = r.matcher(ip); return m.matches(); } public static void main(String[] args) { String content = "123.2.1.2"; System.out.println(isIp(content)); } }