import java.nio.file.Path;
import java.nio.file.Files;
import java.util.stream.Stream;
import java.io.IOException;
public class Crawler
{
    public static void main(String[] args)
    {
        String dirName = args[0];
        String extension = args[1];
        if(args.length < 2)
        {
            System.err.println("Malformed request!");
            System.err.println("usage:  java Crawler direcory extension");
            System.exit(1);
        }
        /* search directory dirName and list all files
            having the specified extension*/
        //create a path to the directory
        Path pathToDir = Path.of(dirName);
        if(!Files.isDirectory(pathToDir))
        {
            System.err.printf("File %s is nonexistent or not a directory\n",
                pathToDir);
            System.exit(1);
        }
        try
        {
            Files.list(pathToDir)
                .filter(e -> e.toString().endsWith("." + extension))
                .forEach(System.out::println);
        }
        catch(IOException ex)
        {
        }
        //filter for our extension
    }
}