I add some codes in android studio after run it shows error class,interface and enum expected in codes

i add some codes in android studio after run it shows error class,interface and enum expected in codes and here is codes--------------------

import com.apptracker.android.listener.AppModuleListener;
import com.apptracker.android.track.AppTracker;
// Leadbolt SDK imports
 
public class MainActivity extends Activity {
       
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        if(savedInstanceState == null) {
            // Initialize Leadbolt SDK with your api key
            AppTracker.startSession(getApplicationContext(),"YOUR_APP_API_KEY",AppTracker.ENABLE_AUTO_CACHE);
        }
        // cache Leadbolt Ad without showing it
        AppTracker.loadModuleToCache(getApplicationContext(),"inapp");
    }
 
    public void gameOver() {
        // call this when you want to display the Leadbolt Interstitial
        if(AppTracker.isAdReady("inapp")) {
                AppTracker.loadModule(getApplicationContext(),"inapp");
        }
    }
}