Importing Java Library JAR into eclipse

问题

I'm currently trying to implement a browser with pipelining feature in it. The problem is in order to code the HTTP pipeline, i need the support of a library. I tried to import it to my workspace by using Project - > properties -> Java build path ->addJar. And I was able to add it successfully. But now my problem is, even though it is added to my workspace it doesnt let me run this code. It gives me errors as if I have not imported the library:

package com.test.download;
import java.util.Collections;
import org.factor45.*;
    public class Example {

        // Execute the request
        HttpRequestFuture<String> future = client.execute("hotpotato.factor45.org", 80, request,
                                                          new BodyAsStringProcessor());
        future.addListener(new HttpRequestFutureListener<String>() {
            @Override
            public void operationComplete(HttpRequestFuture<String> future) throws Exception {
                System.out.println(future);
                if (future.isSuccessfulResponse()) {
                    System.out.println(future.getProcessedResult());
                }
                client.terminate();
            }
        });
    }

This is available in the same website which provided me the library for the above code. "Here" is the website for your reference. Also you can find the JAR file inside this website.

Please help me to figure out the problem. If you solve this you are a life saver! Thanks in advance!