Why this java link checker code does not compile?

Question

I already read the link checker question posted in SO. If there are more questions of this kind and I missed them, my apologies.

We need to find broken links in a website in a very easy way and scriptable way, so we can document the links that are broken. I found a blog post with some code written in java that will do exactly what I need, and my very basic knowledge let me compile it, but I get errors every time. I thought that maybe someone here might be able to direct me to why the code does not compile.

Here is the code:

import java.net.HttpURLConnection;
import java.net.URL;
class links
{

private static boolean isLive(String link) {
    HttpURLConnection urlConnection = null;
    try {
      URL url = new URL(link);
      urlConnection = (HttpURLConnection) url.openConnection();
      urlConnection.setRequestMethod("HEAD");
      urlConnection.connect();
      String redirectLink = urlConnection.getHeaderField("Location");
      if (redirectLink != null && !url.equals(redirectLink)) {
        return isLive(redirectLink);
      } else {
        return urlConnection.getResponseCode() == HttpURLConnection.HTTP_OK;
      }
    } catch (Exception e) {
      return false;
    } finally {
      if (urlConnection != null) {
        urlConnection.disconnect();
      }
    }
  }

  public static void main(String[] args) {
    System.out.println(isLive("http://www.fakelink.net"));
  }
}

Thanks to all that reply. I putting the code that compiles here, for future reference.

Answer 1

The code seems correct. May be you have not imported the required Packages. It will help if you could post the compiler errors that you are getting.

Answer 2

You need to have the proper packages imported. In this case, you should have the follow at the top of the file:

import java.net.HttpURLConnection;
import java.net.URL;

I'm also getting a compiler warning on the following piece of code:

 && !url.equals(redirectLink)

It's trying to equate url (which is a URL) to redirectLink (which is a String). In Java it will automatically compare the string value when this happens and the toString actually gives what you want. To be more precise in the authors code I would change the above code to:

 && !url.toExternalForm().equals(redirectLink)

Note: In netbeans, you can simply right click and select the option Fix Imports (or hit Ctrl + Shift + I) and it will try to find the correct packages that you're currently using and automatically insert the import statements.