Programs that interact with the Internet might have the need to validate if a URL is valid. For instance, you might have a enter their URL on a comment made on your website or be accepting a feed from a third party application where you want to validate the URI to ensure proper formatting. This example will show how to check if a URL is valid URL using java regular expression, guava and apache commons.
Straight up Java
Using a java regular expression we will validate if a URL is valid.
Feature request 1191 URLValidator exists in guava's backlog.
Based on php script Apache commons URL UrlValidator has a series of routines or behavior that is checks for to validate a URL.