Here you can find the source of isIp4Address(String text)
public static boolean isIp4Address(String text)
//package com.java2s; import java.util.regex.Matcher; import java.util.regex.Pattern; import android.text.TextUtils; public class Main { public static final String regIpAddress = "^([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])$"; public static boolean isIp4Address(String text) { if (TextUtils.isEmpty(text)) { return false; }/*from w ww. j a v a 2s. c o m*/ Pattern pattern = Pattern.compile(regIpAddress); Matcher macher = pattern.matcher(text); return macher.matches(); } public static boolean isEmpty(String text) { if (text == null || text.length() == 0) { return true; } return false; } }