Java tutorial
//package com.java2s; import java.net.URL; public class Main { public static String validateIcalUrl(String url) { url = url.replace("page=calendar", "page=ical"); if (!isValidURL(url)) return null; return url; } public static boolean isValidURL(String url) { try { new URL(url).toURI(); // this is made to check whether its a valid URL return true; } catch (Exception ex) { return false; } } }