A Java small class to read the lines from a given URL location/webpage and print each URL that is a link from another defined website. The library edu.duke is a dependency for the class to work, it should be added into the Java IDE to compile with no errors. Download link http://www.dukelearntoprogram.com/downloads/archives/courserajava.jar

FindWebLinks.java

/**
 * Read the lines from a given URL location and prints each URL that is a link from a defined website.
 * E.g. All links matching youtube.com.
 * 
 * @author (Elvis Morales) 
 * @version (1.0)
 */

import edu.duke.*;
import java.io.*;

public class FindWebLinks {
    
    public void findLinks() {
        
        URLResource webPage = new URLResource("http://www.billboard.com/articles/news/6836078/youtube-fan-uploaded-music-videos-2015"); 
		for ( String word : webPage.words() ) {
		    
		    String wLow = word.toLowerCase();
		    
			if ( wLow.contains( "youtube.com" ) && ( wLow.contains( "https://" ) || wLow.contains( "http://" ) ) ) {
			    
			    int startQuote = wLow.indexOf("\"");
			    int endQuote = wLow.lastIndexOf("\"");
			    String ytLink = word.substring( startQuote+1, endQuote );
			    System.out.println( ytLink );
       
            }
			
		}
        
    }
    
}