Crawler4j runtime error

I have implemented a web crawler using the crawler4j library. I am encountering the following error:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

I searched for the error on Google and found that slf4j library is missing. So I downloaded the same and added it to the project after which I am getiing the error shown in the snapshot below:

The code of the class is as follows:

import edu.uci.ics.crawler4j.crawler.CrawlConfig;
import edu.uci.ics.crawler4j.crawler.CrawlController;
import edu.uci.ics.crawler4j.fetcher.PageFetcher;
import edu.uci.ics.crawler4j.robotstxt.RobotstxtConfig;
import edu.uci.ics.crawler4j.robotstxt.RobotstxtServer;

public class Controller {

    public static void main(String[] args) throws Exception {

        String crawlStorageFolder = "/DA Project/Crawled Data";
        int numberOfCrawlers = 7;

        CrawlConfig config = new CrawlConfig();
        /*
         * You can set the location of the folder where you want your crawled
         * data to be stored
         */
        config.setCrawlStorageFolder(crawlStorageFolder);
        /*
         * Be polite: Make sure that we don't send more than 1 request per
         * second (1000 milliseconds between requests).
         */
        config.setPolitenessDelay(1000);

        /*
         * You can set the maximum crawl depth here. The default value is -1 for
         * unlimited depth
         */
        config.setMaxDepthOfCrawling(-1);

        /*
         * You can set the maximum number of pages to crawl. The default value
         * is -1 for unlimited number of pages
         */
        config.setMaxPagesToFetch(-1);
        /*
         * This config parameter can be used to set your crawl to be resumable
         * (meaning that you can resume the crawl from a previously
         * interrupted/crashed crawl). Note: if you enable resuming feature and
         * want to start a fresh crawl, you need to delete the contents of
         * rootFolder manually.
         */
        config.setResumableCrawling(false);

        PageFetcher pageFetcher = new PageFetcher(config);
        RobotstxtConfig robotstxtConfig = new RobotstxtConfig();
        RobotstxtServer robotstxtServer = new RobotstxtServer(robotstxtConfig,
                pageFetcher);

        try {

            CrawlController controller = new CrawlController(config,
                    pageFetcher, robotstxtServer);

            /*
             * For each crawl, you need to add some seed urls. These are the
             * first URLs that are fetched and then the crawler starts following
             * links which are found in these pages
             */
            controller
                    .addSeed("http://www.consumercomplaints.in/?search=chevrolet");

            /*
             * Start the crawl. This is a blocking operation, meaning that your
             * code will reach the line after this only when crawling is
             * finished.
             */
            controller.start(MyCrawler.class, numberOfCrawlers);
        } catch (Exception e) {
            System.out.println("Caught Exception :" + e.getMessage());
            e.printStackTrace();
        }

    }
}

Any help would be appreciated. Thank You!

I removed the SLF4J jar file and downloaded the logback 1.1.2 jar file and added it to my project.

The link to the logback API is : http://logback.qos.ch/download.html

Jars included are:

logback-access-1.1.2
logback-access-1.1.2-sources
logback-classic-1.1.2
logback-classic-1.1.2-sources
logback-core-1.1.2
logback-core-1.1.2-sources

Hope others are benefited. Thank You.