/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
        // a cleaner way with `replaceAll`
        String text = "Sites www.google.com и www.ridd.rdd..com good.";
        System.out.println(text.replaceAll("\\b(?!\\S*\\.{2})w{3}(\\.\\w+)+[a-z]{2,6}\\b", "http://$0"));
	}
}

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