Android : Why do i get this error? "Syntax error on token "implements", @ expected"

I get a error at implementation. The error says " Syntax error on token "implements", @ expected " . Why do i get this error and how do i fix this?

And since i'm new to android what does implementation keyword do?

package com.fortuna.cinemalk;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;

import com.actionbarsherlock.ActionBarSherlock.Implementation;
import com.actionbarsherlock.app.ActionBar;
import com.fortuna.cinemalk.service.CommonVariable;
import com.fortuna.cinemalk.service.ScreenSizeIdentifier;
import com.jeremyfeinstein.slidingmenu.lib.SlidingMenu;
import com.jeremyfeinstein.slidingmenu.lib.app.SlidingFragmentActivity;

public class MainActivity extends SlidingFragmentActivity {



    implements HeadlinesFragment.OnHeadlineSelectedListener{

        public void onArticleSelected(int position) {
            // The user selected the headline of an article from the HeadlinesFragment
            // Do something here to display that article

            NewsFramgment articleFrag = (NewsFramgment)
                    getSupportFragmentManager().findFragmentById(R.id.list);

            if (articleFrag != null) {
               System.out.print("no news found");

            } else {
                // Otherwise, we're in the one-pane layout and must swap frags...

                // Create fragment and give it an argument for the selected article
                NewsFramgment newFragment = new NewsFramgment();
                Bundle args = new Bundle();
                args.putInt(NewsFramgment.ARG_POSITION, position);
                newFragment.setArguments(args);

                FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

                // Replace whatever is in the fragment_container view with this fragment,
                // and add the transaction to the back stack so the user can navigate back
                transaction.replace(R.id.content_frame, newFragment);
                transaction.addToBackStack(null);

                // Commit the transaction
                transaction.commit();
            }
        }