How to extract the relative url from the absolute url in Java

You could use the getPath() method of the URL object:

URL url = new URL("https://asd.com/somestuff/another.html");
System.out.println(url.getPath());  // prints "/somestuff/another.html"

Now, this only brings the actual path. If you need more information (the anchor or the parameters passed as get values), you need to call other accessors of the URL object:

URL url = new URL("https://asd.com/somestuff/another.html?param=value#anchor");
System.out.println(url.getPath());  // prints "/somestuff/another.html"
System.out.println(url.getQuery()); // prints "param=value"
System.out.println(url.getRef());   // prints "anchor"

A possible use to generate the relative URL without much code, based on Hiru's answer:

URL absolute = new URL(url, "/");
String relative = url.toString().substring(absolute.toString().length());
System.out.println(relative); // prints "somestuff/another.html?param=value#anchor"

if you know that the domain will always be .com then you can try something like this:

String url = "https://asd.com/somestuff/another.html";
String[] parts = url.split(".com/");
//parts[1] is the string after the .com/