Getting this errror Bummer: Looks like you forgot to call 'onResume()' from the parent Activity.

import android.os.Bundle;
import android.view.View;

public class TimeTravelActivity extends Activity {

  public String targetYear;

  private NetworkConnectionReceiver receiver = new NetworkConnectionReceiver();

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_time_travel);

    Intent intent = getIntent();
    targetYear = intent.getStringExtra("EXTRA_YEAR");
    EnergySource source = (EnergySource)intent.getParcelableExtra("EXTRA_ENERGY");

  }
  @Override
  protected void onResume(){
    IntentFilter intent = new IntentFilter("android.net.conn.CONNECTIVITY_CHANGE");
    registerReceiver(receiver, intent);
  }

  @Override
  protected void onPause(){
    unregisterReceiver(receiver);
  }
}